*PLEASE READ THIS COMMENT AND THE VIDEO DESCRIPTION FOR HELPFUL INFORMATION* After doing more research and asking questions on a Toyota forum, it seems the consensus is the downstream O2 sensor is just for monitoring the catalytic converter function and has nothing to do with regulating the Air/Fuel mixture. I'm still not 100% convinced this is the case and I'm fine with the fact I might have wasted money replacing the downstream O2 sensor. I have gone through a couple tanks of fuel since doing this job and it does appear I have improved my gas mileage. But, since it's hard to duplicate the exact driving conditions before the job, I can't say for sure how much it improved. Before the job, the best mpg I saw was 15.4 and that was mostly highway driving with some city driving. After the job, I went through a tank of fuel with similar driving, mostly highway with some city and I got 16.7 mpg. When I did 100% highway, I recorded 19 mpg.
I got about the same increase after replacing the sensors on my 1997 4Runner. The increase was just under 1mpg. Now I get consistently over 18mpg. This has been repeated now after several refills. This is with a combination of highway and city driving. Not a huge increase but any increase is good. I haven’t tried 100% highway driving yet. I used to get 21.5 mpg on the highway when it was new. If I can reach 22mpg on the highway it would be great. I have 397k miles on the car.
At 20 years / 170k miles I'm looking at doing this for my 2000 4Runner. Come to find out that after 99 you also need to look and see if your vehicle is Calif or Federal EPA emissions. The Calif emissions vehicles have AFR (air fuel ratio) sensor for the upstream and basic O2 sensor downstream. Federal EPA (non Calif) vehicles use the same O2 sensor for both the upstream and downstream sensors. Additionally manual transmissions and 4wd/2wd all use different sensors.
My engine had no codes but when I replaced both o2 sensors, I’m getting way better mpg and now the engine feels like factory smooth. The truck has never felt this smooth. Not ever. It feels amazing. So happy, it’s like a brand new truck.
My 2001 3.4 V6 Tacoma had a CEL for P0420 recently. I changed the upstream 02 Sensor. Denso of course. After the change I drove about 20-30 miles and light went off. I am the original owner and in my experience the P0420 is always the 02 sensor. Thanks Tim.
@@tony_lopezyou've gotta use a scan tool to check voltage basically. If your upstream is good and downstream is bad, you either have a bad cat or bad downstream
Hey Timmy I bought your scanning tool/device and worked perfectly with an app car scanner. Almost imidetelly I notice contants 0V reading on my o2 sensor 1 (before cat). Made some basic checks and cosinder it's broken. replaced both sensor (just in case) removed error codes P0171 and P0125 and guess what! No more check engine light. Huge improvement on engine general work. No more missfire, no more high rpm at idle and huge improvemt on MGP. Before replacement I was having 10-13MPG now on highway at 65-70 I am getting 18MPGs. I am so happy with my work. Its a pity we are leaving on differen continents. I would hug You ;)
4 years later...my have times changed. $193 just for the upstream sensor. THANK YOU for saving me a lot of headache. I have a 2000 gen3 4runner (original owner) that I purchased in AZ, it has the CA emissions sticker under the hood. A lot of the parts stores do not even acknowledge this detail, and would have ended up getting wrong part.
@@janaemcdaniel6596Hi. I just bought my upstream from Amazon at $150 alone. Auto parts were charging $200. You got a deal. I changed upstream to clear code p1135, but now I’m getting code p4020. I’m going to change the downstream hoping that will clear the code. Crossing fingers it’s not a bad cat
I just replaced both sensors and it wasn’t too bad. I have a 2002 4Runner SR5, 4WD with 156,000 miles. My specific part numbers are Denso 234-9002 (upstream) and Denso 234-4261 (downstream). All in, it was about $189 which is a far cry from the approximate $800 quote I got from Toyota, wow! Timmy thank you so much for your videos, everything is explained so well it which makes it very doable. From the time I got my truck on ramps to putting my tools away it was about 1.5 hours. Just took my time and had patience getting off a few of the nuts being that everything was original and I live in beautiful Indiana with salty roads!! Anyway thanks a ton TT , do this job yourself guys and save a ton of $$$ and have the satisfaction of doing it yourself!!
Hey Tom, glad the job went well for you. $800 is a crazy amount for this job. I bet it felt good doing your own work and knowing all the money you saved yourself. Great job and you're very welcome. Thanks for taking the time to comment and share your success story with us. Happy Wrenching!
Just finished replacing my upstream o2 with a new denso. No major rust issues but the previous owner rounded both nuts off. Had to use alternate rounds of pb blaster and propane torch to eventually get them off with some vice grip pliers. I was hoping for immediately better mpg but time will tell.
Thanks to your video, I just replaced my upstream and downstream O2 sensor on my '99 4Runner and I feel like my truck has become more fuel efficient. Living in Canada, my downstream O2 sensor gasket was rusted after 20 yrs. My next project is replacing rear wheel seal...I'm watching your video multiple times. Keep up the good work!
Hey Action Jackson, you're name wouldn't be Carl Weathers by chance, eh? Good to hear our videos are helping you out. Good luck with the rear axle seal job. Happy Wrenching!
Have the exact same story. No rust on my truck whatsoever, but the downstream was rusted and corroded and crumbling. The new o2 sensors made a gigantic difference.
As always great video and thanks so much for sharing your experience. I replaced the O2 sensor, cleaned MAF and still got the CEL. Finally replaced the oily crusty PVC valve. No more CEL and better gas mileage.
Just done this on my 04 v6 Manual trans, the sensor was easy to unbolt but getting the wire harness unplug took me a while,the wire went up above the trans I couldn't see so had to do so feeling around I guess Auto and Manual trans are lil different thanks for sharing the info about the downstream and the vid
I'm swapping out the O2 sensors as a last resort to fight my high Idle on my '99 4 rnr. I was chasing a mis-fire and tried Seafoam and the idle bumped up and has continued to climb to 1400-1800 rpm. I have new TPS, IAC, spark plugs and wires, fuel injectors, gaskets, MAF sensor, new hoses from smoke test for vacuum leaks. temp sensor check out OK. No slop in throttle body input shaft. THX for all the great videos, lungfish
Did you find the problem? I just watched a video with the same high rpm problem and it ended up being a bad thermostat not allowing the coolant temp to get hot enough to tell the IAC to close and lower the rpm.
Both O2 sensors on my '96 T100 V6 are original, 128k miles. The nuts are so corroded I've had to order the upper exhaust manifold/catalytic converter pipe as well as the cat. Will have a muffler shop finish the job.
both 02 sensors on my '97 Taco 5VZFE MT are original at 344k miles... had a clutch job done and rebuilt R150F that took 12 weeks to complete with exhaust opened for removal/assembly of the clutch... got the truck back and NOW get 50 miles LESS per tank... is it these 02 sensors? truck has No CEL triggered @davidpenney4171
@@efil4kizum Calculating by tank is not the most accurate way to determine mpg. You fill your tank, reset your trip odometer, and then drive. On your next fill up, you divide the miles you drove by the gallons it took to refill your tank and that's how you properly determine mpg. If you're O2 sensors are original, it wouldn't be a bad idea to replace them. There's no guarantees it will increase your mpg, but there's a chance it will.
@@TimmyTheToolman thank you for the instruction on the best way to measure MPGs... here is how i do it for decades on this truck with an ongoing ledger... i wheel it until the low fuel red light comes on... wheel another 20 miles or so to the next spot for some fresh tacoJuice... fill up until the pump handle clicks. keep pumping the juice in slowly to round it up... i can usually fit in more than an extra gallon before fuel starts spitting back out at me LMAO... Many will frown upon that method but i have YET to find any issues doing this over 200k miles of doing it that way... then normal driving (mostly freeway at 65 to 80 with an occasional 95mph when it needs the exercise) yields very close to 360 miles before the red low fuel light has triggered for 20 miles... now it barely gets to 300 miles on that tank over the past 2k miles... this is called the hardcore TacoLife living midWest style... i wheeled it through the heart of Minneapolis on i94 this week and did NOT SPOT 1 Gen1 Tacoma nor Gen3 T4R... its very sad to be all alone out here in the rusty crusty saltbelt 8^(
Job completed, and check engine light is gone. I had to buy an aftermarket catalytic converter and down pipe from the manifold, both discontinued by Toyota. So this was an expensive repair.
Sorry to be elementary, but do you need to disconnect the battery before you start? Also, is there a way to feel the 14 fp without the torch test tool?
When disconnecting electrical connectors, it's never a bad idea to disconnect the battery. I'm sorry, but I don't understand the second part of your question.
@@TimmyTheToolman I think he's talking about a Torque Wrench. The general feel of 14 FP is a little less than your German measurement that you use, GuetenTeight..
@curt8641 Oh yeah, I think you're right, but the Gudentite spec is universal. Whatever you're tightening, you get it, Gudentite, based on the size of the bolt or nut you're tightening. I learned at a pretty young age how to tighten things without stripping or breaking them. You have to understand mechanical advantage, that a longer lever will allow you to deliver more force than a shorter lever. Lots of people live and die by torque specs. They don't know what to do if they can't get their torque wrench onto a fastener.
@@TimmyTheToolman Thank you for your content Timmy, you're my goto guy, especially for my 4runner issues. I still have some. I"d like to hit you up for some more insight if i could.
I'm not sure. Your vehicle was built to the California emissions spec, so I would assume you would have to use the California spec to avoid a check engine code.
@@TimmyTheToolman I agree just need a second opinion. I have a 2000 model and the upstream part (Denso 234-9002) is expensive compared to the downstream. Oh well. As always, thank you for the quick reply!
I also have the 2000 model federal emission. 234-9002 connector doesn’t match up. So used the Denso 234-4162 which I crossed reference through Timmy Denso link. Replaced PVC valve and clean MAF and inspect hoses for leaks and cracks. No more CEL and back to spec.
Timmy - why didn't you go for the trifecta and clean the throttle-body too. Great walkthru on the O2 replacement. I had to replace the downstream on my 3.4 liter Tundra because the heater element died.
My throttle body was already clean from a recent valve cover gasket job. But yeah, not a bad idea to clean the throttle body and also clean the IAC valve.
Thanks Tim, I changed both O2 sensors today in my '03 Tacoma. Easy-peasy after watching your video. No more check-engine light. I always search your channel before any repairs. Cheers mate!
Do you have a trick to separate the plastic connector? I cannot get the damn thing apart. I'm pushing hard as I can on the tab but not getting it pulled apart and I don't want to maybe pull wires apart.
Try cleaning behind the release button with some electrical contact cleaner. They sell it at auto parts stores. Then, try pushing in on the connector while pushing the release tab and then pull back and hope it releases. Good luck!
Thank you for the info. It worked. Do you happen to know if the rubber part those clips attach too are a replaceable part. If so , can they be just pulled out? My are now not attached . That part held them in perfect location.
If you have a graphing scan tool, monitor both upstream and downstream O2 sensors. If the downstream sensor mirrors the upstream the CAT is dying. The downstream sensor should be steady in its output, as it reports to the PCM how the CAT is responding. Great video as always my brother Tim!!
Thanks for the info Brother Jake. I have that Torque Pro app but I don't think that would offer the information you're talking about. Somebody else mentioned using Techstream but it requires a windows based operating system and all I have is a Mac now.
Tim, I know this isn't the subject of this video, but it's nearby. I suspect maybe my Catalytic Converter is bad, I'm suffering a loss of acceleration/power. I don't suspect an engine problem. The 99 4Runner with 3.4L has 380,000 miles on it with the original Cat. Would that mileage alone be enough for the Cat to fail, or would there HAVE to be some underlying problem? Voltage fluctuates below .7v. I know that is a symptom. I'll do a temp test next. Is age alone enough for failure? Thanks!!
You'd have to buy a subscription to Toyota Tech Info. I buy 2-day subscriptions and download what I need. techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&goto=https%3A%2F%2Ftechinfo.toyota.com%3A443%2Fagent%2Fcustom-login-response%3Fstate%3DshJX0Ta1BXIK0Y3GK5F26E-qIeA&original_request_url=https%3A%2F%2Ftechinfo.toyota.com%3A443%2F
hey tim thanks for video up here in WA we dont have emissions anymore we did for awhile ,I am wanting to get rid of the cat converter, cant find anythhing on youtube, can you suggest some ideas or point me in the direction , 2000SR5 4RUNNER THINKING ABOUT PUTTING A V8 IN AROUN 10000 .THANKS TIM ANS SHAWN FOR ALL YOUR GOOD KNO EDGE YOU REALY HELP US OUT ALL THE TOYOT...A WORLD LOVES YOU . DARREN
@@DarrenMyrum Eliminating the catalytic converters is something we don't have experience with since we live in California with strict smog laws. A muffler shop would be able to help you with the job, but dealing with the O2 sensors and the ECU to not have a constant check engine light is something I'm not sure there's a work around, but maybe there is. We have a video for a V8 Swap. th-cam.com/video/Fce7IgMTdKg/w-d-xo.htmlsi=dRvCPHpt0rN4gFKT
Gonna do the down stream on my 02 tacoma and my mechanic suggested to use a 6 piont on the bolts to lessen the chance of stripping. Thanks for the video.
Hey John, yes, a 6 point socket or 6 point box end wrench will definitely lessen the chances of stripping one of the nuts. Your mechanic shared good advice. Make sure to pretreat the nuts with some penetrating oil especially if you have some corrosion. Good luck with the job and Happy Wrenching!
I just did the AFR on my Tacoma. The nuts seem to be made of a softer than normal metal. Make sure whatever tool you decide to use is fully seated on the nut before applying torque.
Thanks for putting this video together. Had to replace the forward o2 sensor on my '98, and this showed me exactly where it was. The flex-head ratchet suggestion made the job a lot easier in the tight space. I still had to fix that the PO put 2 SAE nuts on one of the studs (one too large to touch threads, and the other clamping it down, but screwing up the top threads on the stud), but that's what tap & die kits are for, and even that wasn't hard. The guidance was much appreciated.
Previous owner put SAE bolts in?!? Some things people do is unreal man. Thanks for taking the time to comment and adding your experience to hopefully help others. We really appreciate it Jonathan!!!
I have a 4th runner from 2000. there is another cube in the sensor behind the catalyst and before. I think something is wrong. do you know this problem. Thanks
I'm not exactly sure what you're saying. I don't know what you mean by "cube in the sensor". You will have two sensors, one upstream of the catalytic converters and one downstream of the catalytic converters.
I had to have a new flange made at the exhaust shop. Those studs rust quick. The one they made for me used bolts instead of studs which should last longer with stainless steel bolts.
Timmy i went to denso website & put in my model,year & motor size. Im having a p1135 code. But it doesn't ask if its a California emissions or not. So just order the upstream one. Thanks
Hey Tim !! Are you located in Cali ? I got a CEL on and I need new 02 Sensor. The code calls for the Bank 1 Sensor Number 2, so should I swap both ? And would NGK sensors be just as fine ? I am located in Canada. Was gonna use those same 02 Sensor as you since I have a 4WD automatic 99 4Runner
@@TimmyTheToolman Timmy. Please help ! I already ordered Part Number 234-4162 from Denso. However I am still looking to get the second 02 Sensor I need. In your video you get the 234-4154 however on the website it calls that it is for the manual transmission. I am confused can I just get the same Part number twice and use them both ? Which one do I need ? I have a 1999 4Runner V6 5VZE Not in California. Please someone help ! My truck started running super rough. Very very bad. I also have a lean fuel trim code AND a knock sensors codes.....Got new plugs just trying to order the other 02 sensor I need. Help !!!
@@billythomas4527 Based off what I saw on the Denso website, you would buy the 234-4162 for both the upstream and downstream oxygen sensors. The vehicle I did the video on is a 1998. That's why I have different sensor part numbers. If you do a search for a 1998 with 4wd and an auto trans, you'll see why I used those part numbers.
I have a 98 4 Runner and live in the rust belt of WNY, but the vehicle originally came from Canada. I'm doing a cat back exhaust replacement tomorrow and was curious about the O2 sensor removal. Very informative video.
Timmy, I picked up a 97 with 175k miles and it does not have not the most detailed service records. I had the sparks plugs changed recently by my mechanic. I want to tackle the O2 sensors and MAF, but I also saw the Seafoam treatment you did on your 2000. Would you recommend doing the Seafoam first before changing the O2 sensors and cleaning the MAF?
If would do the seafoam treatment first. You're introducing the seafoam directly into the throttle body so you could clean the MAF before or after because the seafoam isn't going to contact it.
When I removed the gaskets my tacoma, they too were on backwards. I’m not sure if they were changed at some point or if that’s how they came from the factory
Timmy I finally crawled under my rig to look at my upstream sensor to check the condition of the nuts, turns out the nuts are almost completely rusted out and gone. I might have to get a tap and die set to try and salvage the threads. Any advice?
Hard to say. If the studs are too far gone, your best bet might be going to a muffler shop so they can weld on a new O2 sensor bung for you. It probably wouldn't cost you that much.
You could but it's really not necessary for fear of shorting something out. I don't know if one of the wires in these plugs has a 12V constant, but even if they did, you'd have to try to ground it out since the connectors are recessed in the plugs. It would be beneficial though to reset the ECU so the computer will more quickly adapt to the new readings it's getting from the sensor. So, for this reason, disconnecting the battery and resetting the ECU would be a good idea. Thanks for the comment.
No, I didn't cover it. If you have big pieces of gasket to remove, it might be a good idea to cover the hole so the debris doesn't get stuck either in the catalytic converter or muffler.
I loved watching your video. I got a 97 4runner limited with 178,000 miles in it. I went for my biennial smog certification at a star certified station and it failed because the NOx was too high. The mechanic told me that it might be the oxygen sensor. My question is do I need to change both sensor or I can do with the upstream sensor only. One more thing Timmy, I tried another Star certified smog station because I wasn't sure about the first one maybe he just want to rip me off with unnecessary repair and sure enough my truck pass the inspection.Thanks for any reply.
The site didn't prove useful for me to find downstream 02.. It only listed a part number for 02 sensor with no plug terminal. I found another denso with pigtail that claims to be the downstream/cali emissions.. But I don't trust anything on these sites..some don't even have a part number. btw, amazon has identical 02 sensors with same part number and they are WAY cheaper than local auto parts stores or other sources, as the video host related. Oriellys wants 105 plus tax, whearas amazon is 55!
That's interesting the Find Your Part website didn't work out. Both times I replaced O2 senskrs on my 3rd Gen 4runners, I got the part numbers from that site and ordered them from Amzon for the same reason you mentioned.
I’m having the same problem with my 95 4Runner, I think I might follow your lead and replace my sensors as well I’m getting around 15 mpg on a good day lol
I have an old LS400 with 300k miles and it was burning more fuel than my Land Cruiser. LS400 dual exaust and it has 4 O2 sensors. Before replacing sensors it was doing 6 MPG after O2 sensors now the mileage has greatly improved.
Heat, penetrating oil and see if you can clamp onto them with some vice grips to spin them off. They also make nut and bolt extractors like these that would be the right tool for the job. Bolt Biter Extraction Socket Set amzn.to/32YpFOh
I've got to do this to my 99 SR5 Highlander edition. It's 48 state Federal living in the great state of CA, you don't even want to hear my unnecessary California Smog issue story. But, it's been getting poor MPG, like maybe 15. I've been trying to figure it out, stumbled onto the O2 sensor idea in a forum, and thankfully the great TimmyTheToolman has addressed it in a video. I'm hoping to get at least 2 MPG more after this. It's running slightly oversized tires, but has been since I bought it 10 years ago.
Will do. I'm going to take a few tanks and get a good avg. mapped out. Will try to get an idea of specific Hwy avg. too. But I've been trying to figure out my MPG drop off and on for a while now. Was considering the deckplate mod, and even bought an Airaid wondering if the cracked rubber on OEM intake tube was a problem. It's been tuned up, cleaned up the throttle body, MAF etc. I'm hopeful with the O2 sensor/s, just deciding weather to do both. Might as well I guess. 177k, from Utah, so salted roads, and Sacramento summers. These 3rd gens are tanks, but I am eyeing a LX470, or newer 4Runner. With my mileage so poor, a LC or LX isn't much different..
@@TimmyTheToolman It seems to just be the driving conditions for my MPG. Recently we took it for a longer, mostly freeway trip and got over 20 mpg with 90% HWY driving. So I have determined it is the driving conditions. Seems to get 14.5 - 16.5, with mostly city z 60% city, but over 20 mog on the HWY. So I am leaving the sensor alone for now. Mine is aeruouslt rusted, so not worth the trouble unless malfunctioning. Hoping for a door lock actuator replacement video, with the cheap motors instead of the full part. My Drivers lock is failing, particularly if the door is getting direct sun. There are write ups on the forums. But I imagine a lot of these are starting go out at this point. Could be worth a video for you, maybe not? Anyway thanks for your vids, they are above and beyond the best... I'm hoping you get into 100 series Landcruisers next, I have been eyeing LX470'S lately..
Yeah, probably a good idea to leave that sensor alone. We will definitely be doing a driver door lock actuator sometime soon. I need it on my 98. My door lock doesn't always open all the way. It closes fine though. Glad you think so highly of our videos. I would actually like to own an old FJ40 or a 1st Gen 4runner.
@@TimmyTheToolman I have a 2002 Toyota 4runner SR5 4wd Automatic w/ 3.4 V6. I found a part number from www.yotadirectparts.com/ using my VIN. I searched some different websites and it looks like Rockauto has the best prices for a Denso. I was just hoping to find Denso's exact part number for this vehicle. The alternate PN (8946735011) for the Denso product on rockauto ( DENSO 2349002) did match the Toyota PN from yotadirect (89467-35011) so I assume I found the right one. Just weird they list an upstream and a downstream when my vehicle only has an upstream.
I have a 2000 Toyota Camry 2.2 l 5sfe motor O2 sensor looks like the one you have in your hand but I could not find one in a parts store in Australia looked online and found something similar that fitted 100 series landcruiser in America I think it's called an E300 not 100% on that one but it said it would fit the land cruiser as well as a Camry is this true
I have no clue. I suggest you look up the part on the Denso Find my Part website we link in the video description and find the correct sensor. You'll get results for the upstream and downstream sensors so be sure to pick the right one and then use that part number to search for it online. Amazon will most likely have it.
Oh wow very good video I have a 1998 Toyota Camry V6 3.0 and im getting ready to do the other upstream 02 sencer cause the same thing my gas mileage is not that good I think it can get alittle better. Plus on my scan tool all the monitors are good but my 02 sensors one is saying incomplete. Bank 1 sencer 2 has to be changed im pretty sure, but my Mechanic is gonna put the scan tool with live data on tomorrow to make sure I change the right sensor. And hopefully my has mileage will go back up, and im gonna have him spray the mass air flow sencer as well
Question: I ordered the correct part for my 02 4R and it does not come with oval plate attached to it?! Toyota says it’s the right part... it appears to just thread in. It’s Denso oem. Have you heard about this? Did they change the 01-02 O2 sensor?
That's weird. As far as I know, none of them thread into the exhaust, they bolt onto it via the studs sticking out that the oval flange of the sensor slides over and the nuts secure it. Sounds like you got the wrong part. Did you look up the part number via the Denso link we provide in the video description? A quick look under your rig will tell you if our original sensors are just like the ones we show in the video. But again in our experience even the 01-02’s have the oval plate gasket to ensure there isn’t an exhaust leak for both the O2 sensor & the air to fuel ratio sensor.
I'm just throwing this out there, someone may actually have an ansr to or at the least a great suggestion for repair. My dads 2002 toyota 4runner had the TRAC OFF and the VSC TRAC light on without the check engine light. I simply disconnected the negative cable for a few minutes and put it back on, it cleared the lights. But in the event that they possibly return, would anyone have experienced this or just know what could be a route to take in clearing them permanently??? Thank guys! And great video, Tim. Keep up the great work!!!
Hey Israel, I don't have personal experience diagnosing this issue but I do know it's come up on T4R.org. I think a Google search will bring you to several forum threads on the subject.
Thank you for the plethora of information! Great video! My mpg is garbage for my '03 SR5 (about 13/city), but of course I have lots of overlanding weight added (skid plates, rock sliders, roof rack, bigger tires, etc.) Evem though I have no codes thrown, I'm wondering how much ROI in mpg I would get for spending $350 on new O2 sensors ('03 takes 2 upstream, 2 downstream.) Is it worth it?
Hard to say if it's worth it Chris. These rigs get crappy mileage when they are weighted down. If anything, maybe just replace the upstream sensor because that's the air/fuel sensor.
I"m with Tim on this, Mine gets less than acceptible gas mileage, So i look at it this way, Spending the money may not be worth it, but better mileage means better efficiency, which means less stress on the moving parts, less heat, less carbon build up, longer running engine. Money spent VS MPG, no. But worth it? Yes
I'm currently doing research on replacing both my upstream and downstream o2 sensors for my 2001 4Runner SR5 and I have ran into a few questions I can't seem to find the answer to. Does the downstream sensor for certain models have a mounting bracket where as it is screw on for other models? Because everywhere I look suggests that the Denso 234-4261 downstream will fit my model 4Runner despite my current downstream sensor having a bracket like yours in the video. Also, the pin connectors on the o2 sensors that are supposed to fit seem to have the 2 side notches on the wrong side, making it not fit into the female end. Are you aware of any changes in the pin connector between the older and newer gen 3s? Finally, are the sensors you linked in the description the same part? I understand you used one for upstream and one for downstream in the video, however they look identical and am wondering if they can be used interchangeably since the pin connectors are also the same? First and hopefully last time doing this job, thanks!
@frosteddonut06 All I know is I looked up the sensors I needed on the Denso site, ordered them, and they were correct. Maybe your exhaust was changed, and/or the previous owner did something hoakie with the truck.
@@TimmyTheToolman Yeah I got it from a guy that worked at a Toyota dealership so I'm sure there's some stuff I'll be discovering for years to come. Thanks for the info regardless.
found the info i needed in your video description! was worried I didn't get the right sensors but mine is a '96 and I have two of the same 02 sensors so I should be all set. Thanks for all your help!
You certainly could use anti-seize if you want. We don't have bad corrosion issues in the area of California where we live so it's usually not a problem to get fasteners loose. I would not recommend thread locker because it's not necessary for this application.
Great video. Very informative. So I will be replacing the o2 sensors on my 97 4runner. Got a system too lean code and My question is how can you tell the difference between the upstream and downstream sensor? I don't want to mix them up when I replace them. Thanks!
Well, just replace them one at a time and you can't mix them up. They have different part numbers so keep them in the box until you're ready to install them.
I bought mine used and when I changed the plugs recently it had single electrode plugs, I reinstalled the doubles as stated. Been doing lots of cleaning to the engine trying to get my mpg up. I am changing the o2 sensor tomorrow. Hope it works.
Timmay, to speed up the EFI recalibration you should pull the EFI fuse for an hour or so. This will erase all data it's using and start you fresh. Good video, and good information all around!
Correct me if I'm wrong but I looked up on All Data my codes which are P2241 and P2238 for my 03 4Runner sport. Those would be the sensors right next to the manifold on the 4th gen correct? And they're upstream AFR sensors?
Hey Fredy, I found this link and I think you will find if helpful: www.autocodes.com/qa/51208/what-do-codes-p2238-p2241-mean-for-2004-toyota-4runner-sr5-v6
@@TimmyTheToolman No code. I called them to verify and now they're saying it's the Fuel to Air Ratio Sensor. Hmm.. that's not what they said the first time 🤔
@@andyz3925 Ok, here's what you do. Buy the Torque Pro app. It's like $5. Get this Bluetooth OBD II reader: amzn.to/2BeQUsM and also get this on/off switch amzn.to/2WDL4dl because the reader will draw power from your battery even when the vehicle is off. This way you can leave the reader connected at all times and not worrying about draining power from your battery. You can figure out where you want to mount the reader. On my 98, I used double-sided velcro and attached it to the side of the plastic console near where the side of your right leg would be, sort of below and to the left of the ash tray. On my 2000, I also used double-sided velcro but was able to put it in the little cubby space below the ashtray area. For the extra switch cord, I just folded it up and put a ziptie around it to keep it out of the way. With this set-up, you can read your own CEL codes, erase codes and monitor things while you're driving like coolant temp, charging volts and trans temp. If you have a 1999-2002, you can read trans temp info. If you have a 1996-1998, you won't be able to get trans temp info and will have to install an aftermarket gauge like I did on my 98.
I know you’re really good at answering questions when you’re able to when you have the time really appreciate the videos to I’m over here in New Hampshire Jerry’s got a Camry we just ran into the California situation with the Cadillac converter the exhaust is rotted the converter still good anyways I have a 02 Tacoma fortunate that the salt hasn’t gotten to it I keep it under coded got it in good shape anyways the door tag says California but underneath the hood on the left side it says Canada I’m not sure how to find out about the O2 sensors And if we have to go with a California O2 sensor or if there is even The same situation with emissions I guess on what part of the tag would tell you the mechanic figure it out the California thing with Kari’s car thanks again for your time
I replaced my fuel injectors on my 2000 t4r l after watching your video on that. And my mpg actually went down. Could the o2 sensor be the culprit? I have lifted it and put bigger tires on it since then so my mileage has decreased some more. But before I replace the injectors I was averaging around 19 and after I was only averaging 16 to 17. Also recently I have notice a stumble or hesitation every now and then. Seems to happen under light to medium acceleration and the engine will just seemingly lose power for a second. And it also does it at idle sometimes. Any thoughts?
@@sawyerbeals5105 Hard to say what the issue is. Could be a fuel delivery issue. It could be tune-up related like worn spark plugs or a faulty spark plug wire or coil pack. It could be an issue with the throttle body, maybe the throttle position sensor.
Hi Timmy,is there a drive cycle instruction procedure on your manual to reset the catalyst monitor? seems like alot of people are having trouble activating their catalyst monitor sensor after disconecting the batery and there is a debate on how to activate your I/m monitor sensors for a smog check. if you can answer this question and make a video I think it will help a lot of toyota owners and thanks for all the awesome videos you have made.
Francisco Valle if I remember correctly from a recent smog on one of our many 4runners, the procedure to reset the emission systems basically requires you to drive at or above 55 mph for 20-30 minutes. Sean has recently replaced an 02 sensor and took it to the smog shop and they said the system want ready yet and to drive it for 30minutes however we learned later that it’s 20-30 minutes at approximate highway speeds.
I have 4th gen 4runner 2003 model and it consume 19 liter of petrol for 100KM and I have replace almost all the required components like airfilter, spark plugs, cleaned throttle but still poor fuel encomy So the only option is to replace all the four oxygen sensors but the question is: there is no check engine sign on? So what do u suggest based on your experience???
From what I understand, and I talk about this in the video, an air/fuel or O2 sensor can get lazy but not necessarily throw a failure code. When they get lazy, they might not be sending back accurate info to the ECU to adjust the air fuel mixture optimally. That's the theory. It's the upstream sensors that mostly deal with adjustments to the air/fuel mixture. The downstream ones are just monitoring mostly to verify the effectiveness of the catalytic converters scrubbing the exhaust gases. So, if you're going to replace them, I'd try just the upstream ones and see what happens.
Check your MAF first. It’s usually in or close to the air box where the air filter lives. You can clean it with MAF sensor spray and sometimes, it solves a lot of problems with the air and fuel ratios.
Are these sensors California Compliant? I only ask because when I go to search for oxygen sensors for my 1999, it gives me multiple "Exc. Calif" plugs and a couple that are for "Calif" mine come up with different part numbers as well.
This is the confusing part and I decided to not worry about it. The Denso website says nothing about California spec or Non-California spec for my 98. I just plugged in my Year, Make, Model and Engine and it spit out all the results. Then, I just chose the right sensor based of my transmission (auto or manual) and whether I had 2wd or 4wd. And, so far so good. No CELs and it appears my gas mileage improved. It seems the California Spec upstream Air/Fuel Sensors and California Spec O2 Sensors started in 1999.
I had the same problem for my 00. After some research I found out 99and 00 we're the only Cali specific emission models. The 02 sensors also look different. The one Timmy has is for federal emissions. You will see the federal sensor has a million holes while the Cali sensor has 4 holes. If I remember correctly the denso part numbers are...upstream part number is 234-9002( automatic transmission)/ 234-9003(manual transmission) and the downstream is 234-4153." Hope that helps.
Hi Timmy Great vídeo! The check engine light of my 4runner 96, just turn on, troubleshooting P0420. 1.- Catalytic converter with defects 2.- operation condition o motor fail 3.- vacuum considerable leak. Based in your experience, do you know the probable cause of this code?
Hey Javi, this P0420 code, like many CEL codes can have many different causes. This code pops up due to the downstream O2 sensor picking up a problem with the exhaust gases it's reading. The sensor is saying there's a problem with the Catalytic Converter Efficiency. If it were me, I'd first try replacing the downstream O2 sensor and see where that gets me. Your last resort is actually replacing the catalytic converter(s) because that's lots of money.
On my 2000 Tundra the downstream O2 sensor on passenger side. There isn't a nut on the bottom from the corrosion the top one is corroded so bad I can fit a 10mm socket on it fits to an extent, it's like half a nut holding onto the bolt. What do I do? I can't get it off for anything.n
With that level of corrosion, I think going to a muffler shop might be your best bet and see what they think is the easiest and most affordable fix. With the stud gone on one side, even if you got the other nut off, you won't be able to get the new one properly secured.
Hey Timmy, love your videos. I have a 19 T4R Pro, 16 Tundra, 1986 T4R 22RTE and a 96 T100. I reference your videos for jobs I haven’t done. I recently got the P0171 code on my T100. I replaced the spark plugs and wires back in November, radiator and thermostat in February, transmission flush in March. I’ve cleaned the MAF and just changed both O2 sensors. Should I leave the code on and see if it goes away on its own? That way I can see if it’s something else?
Timmy The Toolman I cleared the code after I cleaned the MAF sensor and it came back again when I did that. I’ll clear out the code again now and see what it does. Thanks again!
@@TimmyTheToolman it worked. I cleared the code and so far it hasn't came back on. I could tell the the upstream sensor had more black carbon caked on it and is the one that was possibly throwing the code. Thanks again. -Dan
Hey Timmy, My check engine light came on giving me a code that my rear 02 sensor was the culprit. Quick look underneath and saw that studs were extremely rusted. Brushed them off with wire brush and sprayed them with PB blaster. First nut came off no problem, second nut came off easily to halfway, and then nut started to really make a screeching sound when I turned nut. I would go back and forth with nut spraying with PB blaster and as I got to the last quarter inch the stud started spinning no matter the direction I turned, and then the stud broke off flush. I put new 02 sensor on with one nut and clamped the other side down with a hose clamp as a temporary fix. I turned over 4Runner to see if I could feel any leaks and discovered about three inches in front of 02 sensor on top of the muffler piping there was a nice size leak. Then everything started to make sense. My muffler had to be replaced about a year ago and the muffler shop ended up having to weld the forward muffler pipe to the catalytic converter pipe together because they said the flange rusted out. Well the leak I’m experiencing is exactly at the weld on top of the pipe which is located three inches in front of 02 sensor. I remember the mechanic calling me saying I’d probably have to replace my 02 sensor. I thought at the time how the hell did that go bad. While at that time I had no idea what an 02 sensor was so I asked how much and once he gave me the price I said to hold off if the one is still good. He said he could try putting back on but most likely will have to be replaced soon. Well a few weeks go by and sure enough my check engine light comes on. Take my vehicle to a shop and they confirm my 02 sensor was culprit. They reset check engine light code and said it would come back on most likely and sure enough it did. I then started watching your videos performing maintenance myself saving a ton of money, learning about my vehicle, and slowly acquiring lots of tools. I eventually got my own obd2 reader to monitor my coolant and transmission temp after I installed a cooler as well as used it to check/clear codes specifically the 02 sensor that kept tripping. The only reason I put off replacing 02 sensor for so long is because of all the rust. Anyhow after breaking my stud off I suspect there was no issue with my 02 sensor in the first place and it was the leak in my pipe a few inches ahead of the sensor. Now almost year and half later I am going to call the shop explain the above to them and hope they’ll repair leak in pipe and weld on a stud for a reasonable price considering the circumstances. I am confident that their poor weld job was tripping the 02 sensor code in the first place and they just reset the code before giving my 4Runner back to me. If shop is not willing to offer a reasonable price I might just order everything ahead of tail pipe and replace it myself. My concern will be removing pipe ahead of the cat because of all the rust! Do you see any other options?
Replacing the exhaust manifold on that side might be your only option if it can't be repaired by the muffler shop. I haven't pulled off the exhaust manifolds off an engine inside an engine compartment yet. The only ones I've removed have been from an engine that was already pulled out from a rig. It might be a little tight getting to all the fasteners but I think you shouldn't have too much problem. I guess the rusty nuts would probably be the biggest concern.
We don't have a video for it but its should be pretty easy. The sensor plugs into the knuckle and is secured with a 10mm bolt. You would disconnect it there and then follow the line up until you can find a connection you can disconnect. If it were me, I'd try to find one at a wrecking yard like PicknPull and grab one off a wrecked 1st Gen Tacoma or 3rd Gen 4runner. We do have a video that shows how to disconnect the sensor from the knuckle. In this video, th-cam.com/video/-sY2azyLBuI/w-d-xo.html, go to play time 6:11 and you'll see how we do it.
Did you or have you known anyone had severe problems disconnecting the connection for the air fuel sensor? I was able to remove the rusted bolts but cannot get the cables that rest on top of the transmission visible. I'm beginning to think I will have to lift the body or lower the transmission to get to the connection which seems crazy. Any ideas or pointers?
Hey Shane, I don't understand why you're having trouble disconnecting the air/fuel sensor. The connector you need to disconnect should be visible just like we show in the video.
@@TimmyTheToolman I found the solution in another forum. I have a manual transmission. Apparently they removed the gear shifter and disconnected it from inside. Talk about an obscure find! Going to try it today.
Ah ok. So it sounds like it is on the top of the transmission and they remove the shifter and the boot for easier access from the top. When we did the transmission swap on Sean's rig, some of the connectors are hard to see so you pretty much have to go by feel and find the tab you need to push to disconnect the electrical plug. It's a pain in the ass but it can be done.
@@hunterwerre I'm going to guess you have a manual transmission like me. It took forever to find the answer. The answer is: go through the cab. Take the gear shift and 4x4 knobs off, remove the trim and then you will see a plate. Unbolt the plate and not your looking at the top of the transmission. You can reach but just barely get to the connection and finish your project.
Hey Tim, I live in the great rustbelt state of NJ and have rusted bolts on my upstream o2 AF sensor. 12mm has morphed into something my tools can't get a grip on. With limited space, any ideas on how I can get these rusted bolts off without damaging the threaded stems? Thanks, Joe
Yes, heat and penetrant. Vice grips might work. If the studs for the O2 sensor bung are in bad shape, you might have to pay an exhaust shop to weld in a new one for you.
Go to the Denso Find Your Part website we link in the video description and look up the part numbers. They change based off the year, transmission and whether it's 2wd or 4wd.
@@TimmyTheToolman this is good information. Thank you. I replaced spark plugs, fuel filter, and the upstream and downstream sensor. Haven't been able to drive the distance I have been since but will in a week or so. Average 180 miles to tank, which sparked these repairs. Other deal is what I would consider is excessive heat on the floor of passenger side and center console warming the bottom of my cupholders. This leads me to believe my cat is clogged or partial clogged so that will be next, if I don't notice changes in fuel economy. Thank you sir for all the contributions to the 4runner community, don't know what I would do without your input. Saved me thousands already.
@@keizersoze907 Hey Mark, glad you like the video and you're welcome. Hopefully your mileage improves. As for the heat from the center console, that's most likely just heat coming from the transmission but I guess some radiant heat from the catalytic converter could be affecting it a little bit. Great to hear you've saved a bunch of money doing your own work. Great job and Happy Wrenching!
Hey Daniel, a lot of auto mechanics is pretty straightforward like this job is and it is surprising how much a shop will charge you for something that takes them 15 minutes to replace. This is one of the reasons why we are trying to empower people to do their own work. The other reasons are it's a good learning experience and a skill you can use over and over again, and then there's the great satisfaction you get when you successfully perform a job. Happy Wrenching!
Tim my 99 Ltd 4Runner doesn’t have a cat! Looking at the exhaust I noticed someone took it out and deleted it, the computer is throwing no codes. I’m not sure what to do? Would replacing my upstream help anything?
If your upstream is an air/fuel sensor and not just an oxygen sensor, maybe a replacement could help your gas mileage if your current sensor is a bit lazy and not working optimally. I'm guessing you don't live in a state with strict smog laws. Did they delete the downstream sensor as well?
@@TimmyTheToolman no smog in New Hampshire, truck started its life in Arizona then went to Florida. The truck has both sensors still, also is this something that’s ok to go aftermarket vs oem? Much thanks and happy new year
@@johngacy6367 That is very interesting that you're not throwing a CEL code like P0420 - Catalyst Insufficiency. The front O2 sensor takes a reading of the exhaust gases and then after the catalytic converter scrubs the gases some, the rear O2 sensor should have a different reading letting the computer know the converter is doing it's job. The fact you're not getting a CEL code is perplexing. I wonder if that rear sensor is some type of dummy sensor that always shows the air is good. I would only suggest OEM sensors. I would get the Denso sensors by looking them up in the Denso Find my Part link we provide in the video description. I'm just wondering if you should leave the rear sensor alone. Like I said, I don't understand how you're not throwing a CEL code.
Good video, I have a 0420 code on my 03 tacoma. Have tried sea foam in every way , crakecase, gas, and air intake . The code came back on though, I'm thinking of replacing the up stream o2 sensor, which read 3.00 vts . What you think, thanks for your advise . Kg
If the ohms resistance is out of spec for the O2 sensor, then I'd replace it. I do think a P0420 code would be more of an issue with the downstream sensor. If it's neither the upstream or downstream sensor as the culprit, it may be a situation that you have to replace the catalytic converter. But, if it were me, as a last ditch effort before having to replace a very expensive catalytic converter(s), I'd try a product called Cataclean. It's got mixed reviews but maybe it will work to clean out a partially blocked up catalytic converter and allow the code to go away and you can pass a smog inspection and get your vehicle registered.
*PLEASE READ THIS COMMENT AND THE VIDEO DESCRIPTION FOR HELPFUL INFORMATION*
After doing more research and asking questions on a Toyota forum, it seems the consensus is the downstream O2 sensor is just for monitoring the catalytic converter function and has nothing to do with regulating the Air/Fuel mixture. I'm still not 100% convinced this is the case and I'm fine with the fact I might have wasted money replacing the downstream O2 sensor.
I have gone through a couple tanks of fuel since doing this job and it does appear I have improved my gas mileage. But, since it's hard to duplicate the exact driving conditions before the job, I can't say for sure how much it improved. Before the job, the best mpg I saw was 15.4 and that was mostly highway driving with some city driving. After the job, I went through a tank of fuel with similar driving, mostly highway with some city and I got 16.7 mpg. When I did 100% highway, I recorded 19 mpg.
So long term, did it improve mpg?
My 99 gets about 14 mpg highway, I love it but hate driving it for that reason.
time to get an ecoboost f150 2.7L , lol @@riverahector559
I got about the same increase after replacing the sensors on my 1997 4Runner. The increase was just under 1mpg. Now I get consistently over 18mpg. This has been repeated now after several refills. This is with a combination of highway and city driving. Not a huge increase but any increase is good. I haven’t tried 100% highway driving yet. I used to get 21.5 mpg on the highway when it was new. If I can reach 22mpg on the highway it would be great. I have 397k miles on the car.
At 20 years / 170k miles I'm looking at doing this for my 2000 4Runner. Come to find out that after 99 you also need to look and see if your vehicle is Calif or Federal EPA emissions. The Calif emissions vehicles have AFR (air fuel ratio) sensor for the upstream and basic O2 sensor downstream. Federal EPA (non Calif) vehicles use the same O2 sensor for both the upstream and downstream sensors. Additionally manual transmissions and 4wd/2wd all use different sensors.
Thomas Coolidge should ca 4runner’s change the front afr or o2 sensor first when you get the dreaded CEL?
My engine had no codes but when I replaced both o2 sensors, I’m getting way better mpg and now the engine feels like factory smooth. The truck has never felt this smooth. Not ever. It feels amazing. So happy, it’s like a brand new truck.
That's great you got a good result after swapping out your sensors. Good job!
what year is your rig? 5VZFE engine with a manual transmission?
@jvogler_art4708
My 2001 3.4 V6 Tacoma had a CEL for P0420 recently. I changed the upstream 02 Sensor. Denso of course. After the change I drove about 20-30 miles and light went off. I am the original owner and in my experience the P0420 is always the 02 sensor. Thanks Tim.
You're very welcome. Glad you fixed your issue.
Doesn’t the P0420 code mean it’s a defective catalytic converter (front)? So it can also mean the upstream 02 sensor as well?
@@tony_lopezyou've gotta use a scan tool to check voltage basically. If your upstream is good and downstream is bad, you either have a bad cat or bad downstream
Hey Timmy I bought your scanning tool/device and worked perfectly with an app car scanner. Almost imidetelly I notice contants 0V reading on my o2 sensor 1 (before cat). Made some basic checks and cosinder it's broken. replaced both sensor (just in case) removed error codes P0171 and P0125 and guess what! No more check engine light. Huge improvement on engine general work. No more missfire, no more high rpm at idle and huge improvemt on MGP. Before replacement I was having 10-13MPG now on highway at 65-70 I am getting 18MPGs. I am so happy with my work. Its a pity we are leaving on differen continents. I would hug You ;)
Good to hear you were able to fix your issue and our video assisted you. Thanks for taking the time to comment. We appreciate it!
4 years later...my have times changed. $193 just for the upstream sensor. THANK YOU for saving me a lot of headache. I have a 2000 gen3 4runner (original owner) that I purchased in AZ, it has the CA emissions sticker under the hood. A lot of the parts stores do not even acknowledge this detail, and would have ended up getting wrong part.
You're very welcome Curtis.
That's likely because yours is the CA model. I just bought both upstream & downstream from Amazon, DENSO brand,, for $124 tax & shipping included.
@@janaemcdaniel6596Hi. I just bought my upstream from Amazon at $150 alone. Auto parts were charging $200. You got a deal.
I changed upstream to clear code p1135, but now I’m getting code p4020. I’m going to change the downstream hoping that will clear the code. Crossing fingers it’s not a bad cat
I just replaced both sensors and it wasn’t too bad. I have a 2002 4Runner SR5, 4WD with 156,000 miles. My specific part numbers are Denso 234-9002 (upstream) and Denso 234-4261 (downstream). All in, it was about $189 which is a far cry from the approximate $800 quote I got from Toyota, wow! Timmy thank you so much for your videos, everything is explained so well it which makes it very doable. From the time I got my truck on ramps to putting my tools away it was about 1.5 hours. Just took my time and had patience getting off a few of the nuts being that everything was original and I live in beautiful Indiana with salty roads!! Anyway thanks a ton TT , do this job yourself guys and save a ton of $$$ and have the satisfaction of doing it yourself!!
Hey Tom, glad the job went well for you. $800 is a crazy amount for this job. I bet it felt good doing your own work and knowing all the money you saved yourself. Great job and you're very welcome. Thanks for taking the time to comment and share your success story with us. Happy Wrenching!
Just finished replacing my upstream o2 with a new denso. No major rust issues but the previous owner rounded both nuts off. Had to use alternate rounds of pb blaster and propane torch to eventually get them off with some vice grip pliers. I was hoping for immediately better mpg but time will tell.
Well James, you won the war and that's what counts. Hopefully you'll find an improvement in mpg.
Thanks to your video, I just replaced my upstream and downstream O2 sensor on my '99 4Runner and I feel like my truck has become more fuel efficient. Living in Canada, my downstream O2 sensor gasket was rusted after 20 yrs. My next project is replacing rear wheel seal...I'm watching your video multiple times. Keep up the good work!
Hey Action Jackson, you're name wouldn't be Carl Weathers by chance, eh? Good to hear our videos are helping you out. Good luck with the rear axle seal job. Happy Wrenching!
Have the exact same story. No rust on my truck whatsoever, but the downstream was rusted and corroded and crumbling. The new o2 sensors made a gigantic difference.
As always great video and thanks so much for sharing your experience. I replaced the O2 sensor, cleaned MAF and still got the CEL. Finally replaced the oily crusty PVC valve. No more CEL and better gas mileage.
Good to know you figured out your issue and improved your mpg.
Just done this on my 04 v6 Manual trans, the sensor was easy to unbolt but getting the wire harness unplug took me a while,the wire went up above the trans I couldn't see so had to do so feeling around I guess Auto and Manual trans are lil different thanks for sharing the info about the downstream and the vid
Those connectors can be a pain in the butt to disconnect. Thanks for the comment and you're very welcome.
Same deal on my manual T100. The connector is mounted on top of the tranny.
The sensors in your links say that they don’t fit a 02 4runner. Not sure what year yours is but are all 3rd gens using the same sensors?
They don't all use the same sensors. Use the Denso website link in the video description and look yours up.
@@TimmyTheToolman have you had any issues running denso sensors? Joe joe is saying it will set off my engine light.
@@HT7980 No, I haven't. Denso is the company who made the OEM sensors.
@@TimmyTheToolman that’s what I thought. thanks for the info!
@@HT7980 No problem.
I'm swapping out the O2 sensors as a last resort to fight my high Idle on my '99 4 rnr. I was chasing a mis-fire and tried Seafoam and the idle bumped up and has continued to climb to 1400-1800 rpm. I have new TPS, IAC, spark plugs and wires, fuel injectors, gaskets, MAF sensor, new hoses from smoke test for vacuum leaks. temp sensor check out OK. No slop in throttle body input shaft.
THX for all the great videos,
lungfish
Hope you figure it out.
Did you find the problem? I just watched a video with the same high rpm problem and it ended up being a bad thermostat not allowing the coolant temp to get hot enough to tell the IAC to close and lower the rpm.
Both O2 sensors on my '96 T100 V6 are original, 128k miles. The nuts are so corroded I've had to order the upper exhaust manifold/catalytic converter pipe as well as the cat. Will have a muffler shop finish the job.
Yeah, a muffler shop can install a new O2 sensor bung for you if rust has eaten up too much of the studs.
both 02 sensors on my '97 Taco 5VZFE MT are original at 344k miles... had a clutch job done and rebuilt R150F that took 12 weeks to complete with exhaust opened for removal/assembly of the clutch... got the truck back and NOW get 50 miles LESS per tank... is it these 02 sensors? truck has No CEL triggered
@davidpenney4171
@@efil4kizum Calculating by tank is not the most accurate way to determine mpg. You fill your tank, reset your trip odometer, and then drive. On your next fill up, you divide the miles you drove by the gallons it took to refill your tank and that's how you properly determine mpg. If you're O2 sensors are original, it wouldn't be a bad idea to replace them. There's no guarantees it will increase your mpg, but there's a chance it will.
@@TimmyTheToolman thank you for the instruction on the best way to measure MPGs... here is how i do it for decades on this truck with an ongoing ledger... i wheel it until the low fuel red light comes on... wheel another 20 miles or so to the next spot for some fresh tacoJuice... fill up until the pump handle clicks. keep pumping the juice in slowly to round it up... i can usually fit in more than an extra gallon before fuel starts spitting back out at me LMAO... Many will frown upon that method but i have YET to find any issues doing this over 200k miles of doing it that way... then normal driving (mostly freeway at 65 to 80 with an occasional 95mph when it needs the exercise) yields very close to 360 miles before the red low fuel light has triggered for 20 miles... now it barely gets to 300 miles on that tank over the past 2k miles... this is called the hardcore TacoLife living midWest style... i wheeled it through the heart of Minneapolis on i94 this week and did NOT SPOT 1 Gen1 Tacoma nor Gen3 T4R... its very sad to be all alone out here in the rusty crusty saltbelt 8^(
Job completed, and check engine light is gone. I had to buy an aftermarket catalytic converter and down pipe from the manifold, both discontinued by Toyota. So this was an expensive repair.
Sorry to be elementary, but do you need to disconnect the battery before you start? Also, is there a way to feel the 14 fp without the torch test tool?
When disconnecting electrical connectors, it's never a bad idea to disconnect the battery. I'm sorry, but I don't understand the second part of your question.
@@TimmyTheToolman I think he's talking about a Torque Wrench. The general feel of 14 FP is a little less than your German measurement that you use, GuetenTeight..
@curt8641 Oh yeah, I think you're right, but the Gudentite spec is universal. Whatever you're tightening, you get it, Gudentite, based on the size of the bolt or nut you're tightening. I learned at a pretty young age how to tighten things without stripping or breaking them. You have to understand mechanical advantage, that a longer lever will allow you to deliver more force than a shorter lever. Lots of people live and die by torque specs. They don't know what to do if they can't get their torque wrench onto a fastener.
@@TimmyTheToolman Thank you for your content Timmy, you're my goto guy, especially for my 4runner issues. I still have some. I"d like to hit you up for some more insight if i could.
@@curt8641 You're welcome. What issues does your rig have?
Quick question: If you are no longer living in California can you get the non-California EPA part instead?
I'm not sure. Your vehicle was built to the California emissions spec, so I would assume you would have to use the California spec to avoid a check engine code.
@@TimmyTheToolman I agree just need a second opinion. I have a 2000 model and the upstream part (Denso 234-9002) is expensive compared to the downstream. Oh well. As always, thank you for the quick reply!
I also have the 2000 model federal emission. 234-9002 connector doesn’t match up. So used the Denso 234-4162 which I crossed reference through Timmy Denso link. Replaced PVC valve and clean MAF and inspect hoses for leaks and cracks. No more CEL and back to spec.
Timmy - why didn't you go for the trifecta and clean the throttle-body too. Great walkthru on the O2 replacement. I had to replace the downstream on my 3.4 liter Tundra because the heater element died.
My throttle body was already clean from a recent valve cover gasket job. But yeah, not a bad idea to clean the throttle body and also clean the IAC valve.
Thanks Tim, I changed both O2 sensors today in my '03 Tacoma. Easy-peasy after watching your video. No more check-engine light. I always search your channel before any repairs. Cheers mate!
Glad our video helped you out Damien.
Do you have a trick to separate the plastic connector? I cannot get the damn thing apart. I'm pushing hard as I can on the tab but not getting it pulled apart and I don't want to maybe pull wires apart.
Try cleaning behind the release button with some electrical contact cleaner. They sell it at auto parts stores. Then, try pushing in on the connector while pushing the release tab and then pull back and hope it releases. Good luck!
@@TimmyTheToolman
Thank you for the info. It worked.
Do you happen to know if the rubber part those clips attach too are a replaceable part. If so , can they be just pulled out? My are now not attached . That part held them in perfect location.
@@mcfmwjd I don't know if they are replaceable or not. You can always use zip ties to hold them in place.
Thanks!
You're very welcome!
Do you have a video on the p0446?
Sorry Oscar, we don't.
If you have a graphing scan tool, monitor both upstream and downstream O2 sensors. If the downstream sensor mirrors the upstream the CAT is dying. The downstream sensor should be steady in its output, as it reports to the PCM how the CAT is responding. Great video as always my brother Tim!!
Thanks for the info Brother Jake. I have that Torque Pro app but I don't think that would offer the information you're talking about. Somebody else mentioned using Techstream but it requires a windows based operating system and all I have is a Mac now.
Timmy The Toolman Any hand held graphing scan tool, $200-300 range would work.
Gotcha. I'll have to look into finding a good one.
Tim, I know this isn't the subject of this video, but it's nearby. I suspect maybe my Catalytic Converter is bad, I'm suffering a loss of acceleration/power. I don't suspect an engine problem. The 99 4Runner with 3.4L has 380,000 miles on it with the original Cat. Would that mileage alone be enough for the Cat to fail, or would there HAVE to be some underlying problem? Voltage fluctuates below .7v. I know that is a symptom. I'll do a temp test next. Is age alone enough for failure? Thanks!!
A good muffler shop can tell you if you have a bad cat. They drill a hole and put a probe in to figure out if the cat or cats are bad.
Having trouble getting the bolts removed on a 98 4runner. Any advice? Thanks for a reply.
Heat from a butane torch and penetrating oil. Keep repeating until you get them loose.
I seen you do work on the 4.7. Was wondering if you have or know how to get the complete wire diagram for the O2 sensors on the 4.7 06 4Runner.?
You'd have to buy a subscription to Toyota Tech Info. I buy 2-day subscriptions and download what I need. techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&goto=https%3A%2F%2Ftechinfo.toyota.com%3A443%2Fagent%2Fcustom-login-response%3Fstate%3DshJX0Ta1BXIK0Y3GK5F26E-qIeA&original_request_url=https%3A%2F%2Ftechinfo.toyota.com%3A443%2F
hey tim thanks for video up here in WA we dont have emissions anymore we did for awhile ,I am wanting to get rid of the cat converter, cant find anythhing on youtube, can you suggest some ideas or point me in the direction , 2000SR5 4RUNNER THINKING ABOUT PUTTING A V8 IN AROUN 10000 .THANKS TIM ANS SHAWN FOR ALL YOUR GOOD KNO EDGE YOU REALY HELP US OUT ALL THE TOYOT...A WORLD LOVES YOU . DARREN
@@DarrenMyrum Eliminating the catalytic converters is something we don't have experience with since we live in California with strict smog laws. A muffler shop would be able to help you with the job, but dealing with the O2 sensors and the ECU to not have a constant check engine light is something I'm not sure there's a work around, but maybe there is.
We have a video for a V8 Swap. th-cam.com/video/Fce7IgMTdKg/w-d-xo.htmlsi=dRvCPHpt0rN4gFKT
Gonna do the down stream on my 02 tacoma and my mechanic suggested to use a 6 piont on the bolts to lessen the chance of stripping. Thanks for the video.
Hey John, yes, a 6 point socket or 6 point box end wrench will definitely lessen the chances of stripping one of the nuts. Your mechanic shared good advice. Make sure to pretreat the nuts with some penetrating oil especially if you have some corrosion. Good luck with the job and Happy Wrenching!
I just did the AFR on my Tacoma. The nuts seem to be made of a softer than normal metal. Make sure whatever tool you decide to use is fully seated on the nut before applying torque.
DoubleHaulCharters thanks for the info.
Thank you so much for this video متشکرم از شما آقای محترم
👍🏻
Thanks for putting this video together. Had to replace the forward o2 sensor on my '98, and this showed me exactly where it was. The flex-head ratchet suggestion made the job a lot easier in the tight space. I still had to fix that the PO put 2 SAE nuts on one of the studs (one too large to touch threads, and the other clamping it down, but screwing up the top threads on the stud), but that's what tap & die kits are for, and even that wasn't hard. The guidance was much appreciated.
Previous owner put SAE bolts in?!? Some things people do is unreal man. Thanks for taking the time to comment and adding your experience to hopefully help others. We really appreciate it Jonathan!!!
I have a 4th runner from 2000. there is another cube in the sensor behind the catalyst and before. I think something is wrong. do you know this problem. Thanks
I'm not exactly sure what you're saying. I don't know what you mean by "cube in the sensor". You will have two sensors, one upstream of the catalytic converters and one downstream of the catalytic converters.
The downstream has a longer cable
And it has a different part number too.
I had to have a new flange made at the exhaust shop. Those studs rust quick. The one they made for me used bolts instead of studs which should last longer with stainless steel bolts.
where do you live?... mine came off without a problem... didnt even use penetrating fluid
Just did this job right now, thanks for the videos yall make Timmy and Shawn, i learn alot from them. The results for me were a success.
Good to hear Israel. Glad you had success with this job using our video.
Hey Tim thank you for this detailed instruction.... Your videos are probably the best in their applications and detail! Take care brother! 👍🏞🏜
You're very welcome and we appreciate your compliment. You take care as well.
Timmy i went to denso website & put in my model,year & motor size. Im having a p1135 code. But it doesn't ask if its a California emissions or not. So just order the upstream one. Thanks
You're welcome. Hope it fixes your issue.
Anti-seize on the threads of the mounting studs before putting the nuts on helps the next time the nuts are removed.
Yeah, I agree with that. Thanks for the comment.
Hey Tim !!
Are you located in Cali ? I got a CEL on and I need new 02 Sensor. The code calls for the Bank 1 Sensor Number 2, so should I swap both ? And would NGK sensors be just as fine ? I am located in Canada. Was gonna use those same 02 Sensor as you since I have a 4WD automatic 99 4Runner
I would renew both sensors and use Denso sensors since those are OEM.
@@TimmyTheToolman Timmy. Please help ! I already ordered Part Number 234-4162 from Denso. However I am still looking to get the second 02 Sensor I need. In your video you get the 234-4154 however on the website it calls that it is for the manual transmission. I am confused can I just get the same Part number twice and use them both ? Which one do I need ? I have a 1999 4Runner V6 5VZE Not in California. Please someone help ! My truck started running super rough. Very very bad. I also have a lean fuel trim code AND a knock sensors codes.....Got new plugs just trying to order the other 02 sensor I need. Help !!!
@@billythomas4527 Does your rig have 4wd? Do you have an automatic or manual transmission?
@@TimmyTheToolman Automatic. 4WD yes
@@billythomas4527 Based off what I saw on the Denso website, you would buy the 234-4162 for both the upstream and downstream oxygen sensors. The vehicle I did the video on is a 1998. That's why I have different sensor part numbers. If you do a search for a 1998 with 4wd and an auto trans, you'll see why I used those part numbers.
I have a 98 4 Runner and live in the rust belt of WNY, but the vehicle originally came from Canada. I'm doing a cat back exhaust replacement tomorrow and was curious about the O2 sensor removal. Very informative video.
Good luck with the job. Glad you found the video helpful.
Followed this step by step and the CEL on my 99 SR5 is gone!!! Love this channel
Glad this worked out for you Tito. Thanks for taking the time to comment. Happy Wrenching!
Timmy,
I picked up a 97 with 175k miles and it does not have not the most detailed service records. I had the sparks plugs changed recently by my mechanic. I want to tackle the O2 sensors and MAF, but I also saw the Seafoam treatment you did on your 2000. Would you recommend doing the Seafoam first before changing the O2 sensors and cleaning the MAF?
If would do the seafoam treatment first. You're introducing the seafoam directly into the throttle body so you could clean the MAF before or after because the seafoam isn't going to contact it.
@@TimmyTheToolman Thank you very much.
When I removed the gaskets my tacoma, they too were on backwards. I’m not sure if they were changed at some point or if that’s how they came from the factory
I wonder if the gasket orientation even makes a difference. It might not.
Timmy I finally crawled under my rig to look at my upstream sensor to check the condition of the nuts, turns out the nuts are almost completely rusted out and gone. I might have to get a tap and die set to try and salvage the threads. Any advice?
Hard to say. If the studs are too far gone, your best bet might be going to a muffler shop so they can weld on a new O2 sensor bung for you. It probably wouldn't cost you that much.
@@TimmyTheToolman thanks timmy
@@johngacy6367 No Problem
Should you remove the negative battery terminal first before changing the O2 sensor?? Just saying...
You could but it's really not necessary for fear of shorting something out. I don't know if one of the wires in these plugs has a 12V constant, but even if they did, you'd have to try to ground it out since the connectors are recessed in the plugs.
It would be beneficial though to reset the ECU so the computer will more quickly adapt to the new readings it's getting from the sensor. So, for this reason, disconnecting the battery and resetting the ECU would be a good idea. Thanks for the comment.
Tim. The Denso website doesn't show a diff O2 sensor for Kali versions for 01 or 02 trucks
That's because by that time, trucks across the country were all built to the California spec from what I've heard.
Yes I ordered this one for my 02 and there is no oval plate attached. Just a threaded sensor...
When cleaning the surface for the o2 sensor, did you cover up the hole or no
No, I didn't cover it. If you have big pieces of gasket to remove, it might be a good idea to cover the hole so the debris doesn't get stuck either in the catalytic converter or muffler.
I loved watching your video. I got a 97 4runner limited with 178,000 miles in it. I went for my biennial smog certification at a star certified station and it failed because the NOx was too high. The mechanic told me that it might be the oxygen sensor. My question is do I need to change both sensor or I can do with the upstream sensor only. One more thing Timmy, I tried another Star certified smog station because I wasn't sure about the first one maybe he just want to rip me off with unnecessary repair and sure enough my truck pass the inspection.Thanks for any reply.
If you decide to replace one sensor, I'd suggest going ahead and doing both. That was smart of you to try out a different smog station.
@@TimmyTheToolman Thanks for the good suggestion. You're the man.
@@luisolitoquit4481 You're welcome Luis.
The site didn't prove useful for me to find downstream 02.. It only listed a part number for 02 sensor with no plug terminal.
I found another denso with pigtail that claims to be the downstream/cali emissions.. But I don't trust anything on these sites..some don't even have a part number. btw, amazon has identical 02 sensors with same part number and they are WAY cheaper than local auto parts stores or other sources, as the video host related. Oriellys wants 105 plus tax, whearas amazon is 55!
That's interesting the Find Your Part website didn't work out. Both times I replaced O2 senskrs on my 3rd Gen 4runners, I got the part numbers from that site and ordered them from Amzon for the same reason you mentioned.
I’m having the same problem with my 95 4Runner, I think I might follow your lead and replace my sensors as well I’m getting around 15 mpg on a good day lol
I have an old LS400 with 300k miles and it was burning more fuel than my Land Cruiser. LS400 dual exaust and it has 4 O2 sensors. Before replacing sensors it was doing 6 MPG after O2 sensors now the mileage has greatly improved.
That's good to hear it worked to improve you mpg.
Thank you for the video. I have a problem with rust on mine. The nuts are completely rusted and stripped. Any tips to get them off?
Heat, penetrating oil and see if you can clamp onto them with some vice grips to spin them off. They also make nut and bolt extractors like these that would be the right tool for the job.
Bolt Biter Extraction Socket Set amzn.to/32YpFOh
Their are these extraction sockets they sell at Home Depot give those a try
I've got to do this to my 99 SR5 Highlander edition. It's 48 state Federal living in the great state of CA, you don't even want to hear my unnecessary California Smog issue story. But, it's been getting poor MPG, like maybe 15. I've been trying to figure it out, stumbled onto the O2 sensor idea in a forum, and thankfully the great TimmyTheToolman has addressed it in a video. I'm hoping to get at least 2 MPG more after this. It's running slightly oversized tires, but has been since I bought it 10 years ago.
Hopefully it improves your gas mileage. Let me know how it turn out. I think mine improved a little but it's hard to say how much.
Will do. I'm going to take a few tanks and get a good avg. mapped out. Will try to get an idea of specific Hwy avg. too. But I've been trying to figure out my MPG drop off and on for a while now. Was considering the deckplate mod, and even bought an Airaid wondering if the cracked rubber on OEM intake tube was a problem. It's been tuned up, cleaned up the throttle body, MAF etc. I'm hopeful with the O2 sensor/s, just deciding weather to do both. Might as well I guess. 177k, from Utah, so salted roads, and Sacramento summers. These 3rd gens are tanks, but I am eyeing a LX470, or newer 4Runner. With my mileage so poor, a LC or LX isn't much different..
@@TimmyTheToolman It seems to just be the driving conditions for my MPG. Recently we took it for a longer, mostly freeway trip and got over 20 mpg with 90% HWY driving. So I have determined it is the driving conditions. Seems to get 14.5 - 16.5, with mostly city z 60% city, but over 20 mog on the HWY. So I am leaving the sensor alone for now. Mine is aeruouslt rusted, so not worth the trouble unless malfunctioning.
Hoping for a door lock actuator replacement video, with the cheap motors instead of the full part. My Drivers lock is failing, particularly if the door is getting direct sun. There are write ups on the forums. But I imagine a lot of these are starting go out at this point. Could be worth a video for you, maybe not? Anyway thanks for your vids, they are above and beyond the best... I'm hoping you get into 100 series Landcruisers next, I have been eyeing LX470'S lately..
Yeah, probably a good idea to leave that sensor alone.
We will definitely be doing a driver door lock actuator sometime soon. I need it on my 98. My door lock doesn't always open all the way. It closes fine though. Glad you think so highly of our videos. I would actually like to own an old FJ40 or a 1st Gen 4runner.
Would be great if Denso's "find your part" section of the website worked.
Must be down for some reason. I just checked myself and the site doesn't load. Maybe they'll have it up and running soon.
@@TimmyTheToolman I have a 2002 Toyota 4runner SR5 4wd Automatic w/ 3.4 V6. I found a part number from www.yotadirectparts.com/ using my VIN. I searched some different websites and it looks like Rockauto has the best prices for a Denso. I was just hoping to find Denso's exact part number for this vehicle. The alternate PN (8946735011) for the Denso product on rockauto ( DENSO 2349002) did match the Toyota PN from yotadirect (89467-35011) so I assume I found the right one. Just weird they list an upstream and a downstream when my vehicle only has an upstream.
@@MC-nd3zl You should have a downstream O2 sensor. Something isn't adding up.
@@TimmyTheToolman Whoa......guess I missed the other one the first two times I went under and looked. It does have two!
@@MC-nd3zl That's good. I thought somebody did some janky work on your rig and eliminated the rear O2 sensor.
I have a 2000 Toyota Camry 2.2 l 5sfe motor O2 sensor looks like the one you have in your hand but I could not find one in a parts store in Australia looked online and found something similar that fitted 100 series landcruiser in America I think it's called an E300 not 100% on that one but it said it would fit the land cruiser as well as a Camry is this true
I have no clue. I suggest you look up the part on the Denso Find my Part website we link in the video description and find the correct sensor. You'll get results for the upstream and downstream sensors so be sure to pick the right one and then use that part number to search for it online. Amazon will most likely have it.
Oh wow very good video I have a 1998 Toyota Camry V6 3.0 and im getting ready to do the other upstream 02 sencer cause the same thing my gas mileage is not that good I think it can get alittle better. Plus on my scan tool all the monitors are good but my 02 sensors one is saying incomplete. Bank 1 sencer 2 has to be changed im pretty sure, but my Mechanic is gonna put the scan tool with live data on tomorrow to make sure I change the right sensor. And hopefully my has mileage will go back up, and im gonna have him spray the mass air flow sencer as well
Good luck with the job. Hope the O2 sensor swap fixes your issue and improves your gas mileage.
@Timmy The Toolman Thank you brother
@@williamavery1758 You're welcome.
Did it work for saving gas?
It's hard to say. If it did, it wasn't by much.
Question: I ordered the correct part for my 02 4R and it does not come with oval plate attached to it?! Toyota says it’s the right part... it appears to just thread in. It’s Denso oem. Have you heard about this? Did they change the 01-02 O2 sensor?
That's weird. As far as I know, none of them thread into the exhaust, they bolt onto it via the studs sticking out that the oval flange of the sensor slides over and the nuts secure it. Sounds like you got the wrong part. Did you look up the part number via the Denso link we provide in the video description? A quick look under your rig will tell you if our original sensors are just like the ones we show in the video. But again in our experience even the 01-02’s have the oval plate gasket to ensure there isn’t an exhaust leak for both the O2 sensor & the air to fuel ratio sensor.
Hey dude.. just a question with a multi meter Do you have any idea what the resistance of the bad sensor vs a good one?
All videos should be this good.Thank you
Thanks! We appreciate the compliment.
I'm just throwing this out there, someone may actually have an ansr to or at the least a great suggestion for repair. My dads 2002 toyota 4runner had the TRAC OFF and the VSC TRAC light on without the check engine light. I simply disconnected the negative cable for a few minutes and put it back on, it cleared the lights. But in the event that they possibly return, would anyone have experienced this or just know what could be a route to take in clearing them permanently??? Thank guys! And great video, Tim. Keep up the great work!!!
Hey Israel, I don't have personal experience diagnosing this issue but I do know it's come up on T4R.org. I think a Google search will bring you to several forum threads on the subject.
Is there a way to clean them instead of replacing them??
I've never heard of anyone cleaning them. When the sensors go bad or start getting lazy, people just replace them.
Thank you for the plethora of information! Great video! My mpg is garbage for my '03 SR5 (about 13/city), but of course I have lots of overlanding weight added (skid plates, rock sliders, roof rack, bigger tires, etc.) Evem though I have no codes thrown, I'm wondering how much ROI in mpg I would get for spending $350 on new O2 sensors ('03 takes 2 upstream, 2 downstream.) Is it worth it?
Hard to say if it's worth it Chris. These rigs get crappy mileage when they are weighted down. If anything, maybe just replace the upstream sensor because that's the air/fuel sensor.
I"m with Tim on this, Mine gets less than acceptible gas mileage, So i look at it this way, Spending the money may not be worth it, but better mileage means better efficiency, which means less stress on the moving parts, less heat, less carbon build up, longer running engine. Money spent VS MPG, no. But worth it? Yes
I'm currently doing research on replacing both my upstream and downstream o2 sensors for my 2001 4Runner SR5 and I have ran into a few questions I can't seem to find the answer to. Does the downstream sensor for certain models have a mounting bracket where as it is screw on for other models? Because everywhere I look suggests that the Denso 234-4261 downstream will fit my model 4Runner despite my current downstream sensor having a bracket like yours in the video. Also, the pin connectors on the o2 sensors that are supposed to fit seem to have the 2 side notches on the wrong side, making it not fit into the female end. Are you aware of any changes in the pin connector between the older and newer gen 3s? Finally, are the sensors you linked in the description the same part? I understand you used one for upstream and one for downstream in the video, however they look identical and am wondering if they can be used interchangeably since the pin connectors are also the same? First and hopefully last time doing this job, thanks!
@frosteddonut06 All I know is I looked up the sensors I needed on the Denso site, ordered them, and they were correct. Maybe your exhaust was changed, and/or the previous owner did something hoakie with the truck.
@@TimmyTheToolman Yeah I got it from a guy that worked at a Toyota dealership so I'm sure there's some stuff I'll be discovering for years to come. Thanks for the info regardless.
@@frosteddonut06 Good luck with it.
found the info i needed in your video description! was worried I didn't get the right sensors but mine is a '96 and I have two of the same 02 sensors so I should be all set. Thanks for all your help!
Glad our video could help you out Caleb. Happy Wrenching!
No anti seize or thread locker?
You certainly could use anti-seize if you want. We don't have bad corrosion issues in the area of California where we live so it's usually not a problem to get fasteners loose. I would not recommend thread locker because it's not necessary for this application.
Great video. Very informative. So I will be replacing the o2 sensors on my 97 4runner. Got a system too lean code and My question is how can you tell the difference between the upstream and downstream sensor? I don't want to mix them up when I replace them. Thanks!
Well, just replace them one at a time and you can't mix them up. They have different part numbers so keep them in the box until you're ready to install them.
Did u feel any performance wise?
No, I didn't.
Make sure you have dual electrode plugs. I always find these runners with incorrect spark plugs
Yes, you are correct Rob. Dual electrode plugs are the correct ones for our rigs.
I bought mine used and when I changed the plugs recently it had single electrode plugs, I reinstalled the doubles as stated. Been doing lots of cleaning to the engine trying to get my mpg up. I am changing the o2 sensor tomorrow. Hope it works.
Timmy The Toolman my 4Runner misfires and runs poorly it has single electrode plug do you think that would be related
Timmay, to speed up the EFI recalibration you should pull the EFI fuse for an hour or so. This will erase all data it's using and start you fresh. Good video, and good information all around!
Thanks for the tip. Glad you like the video.
What happens if I cut the wires and reconnect the wires to a different plug? Is the sensor going to work the same or not?
As long as you connect the wires correctly, it will work.
Correct me if I'm wrong but I looked up on All Data my codes which are P2241 and P2238 for my 03 4Runner sport. Those would be the sensors right next to the manifold on the 4th gen correct? And they're upstream AFR sensors?
Hey Fredy, I found this link and I think you will find if helpful: www.autocodes.com/qa/51208/what-do-codes-p2238-p2241-mean-for-2004-toyota-4runner-sr5-v6
Can a leak near(collector area) a Cat cause the engine light to turn on. Our local Autozone guy says its the O2 sensor that needs to be replaced?
An exhaust leak could definitely be the cause for a CEL code to arise.
You are a true professional, explaining and working. My sincere congratulations.
Thanks Ramon. We appreciate the nice compliment. Happy Wrenching!
Just got back from a local shop to figure out my Check Engine light. They say its the "Air Flow Heated Sensor". IS that another word for O2 Sensor?
Sounds like it. Did they tell you the code number? That would help.
@@TimmyTheToolman No code. I called them to verify and now they're saying it's the Fuel to Air Ratio Sensor. Hmm.. that's not what they said the first time 🤔
@@andyz3925 Do you have an Android or Apple phone?
@@TimmyTheToolman Android.
@@andyz3925 Ok, here's what you do. Buy the Torque Pro app. It's like $5. Get this Bluetooth OBD II reader: amzn.to/2BeQUsM and also get this on/off switch amzn.to/2WDL4dl because the reader will draw power from your battery even when the vehicle is off. This way you can leave the reader connected at all times and not worrying about draining power from your battery. You can figure out where you want to mount the reader. On my 98, I used double-sided velcro and attached it to the side of the plastic console near where the side of your right leg would be, sort of below and to the left of the ash tray. On my 2000, I also used double-sided velcro but was able to put it in the little cubby space below the ashtray area. For the extra switch cord, I just folded it up and put a ziptie around it to keep it out of the way.
With this set-up, you can read your own CEL codes, erase codes and monitor things while you're driving like coolant temp, charging volts and trans temp. If you have a 1999-2002, you can read trans temp info. If you have a 1996-1998, you won't be able to get trans temp info and will have to install an aftermarket gauge like I did on my 98.
Thanks for your video!! We need more people like you videoing and explaining your job. Thanks !!!
You're very welcome and thanks for the kind words. Happy Wrenching!
Is Denso a recommended brand? When I look up O2 sensors I see a brand called Moca with quite a few options. And the pricing isn't as much.
You should only consider DENSO. That is the OEM spec.
- Sean
I know you’re really good at answering questions when you’re able to when you have the time really appreciate the videos to I’m over here in New Hampshire Jerry’s got a Camry we just ran into the California situation with the Cadillac converter the exhaust is rotted the converter still good anyways I have a 02 Tacoma fortunate that the salt hasn’t gotten to it I keep it under coded got it in good shape anyways the door tag says California but underneath the hood on the left side it says Canada I’m not sure how to find out about the O2 sensors And if we have to go with a California O2 sensor or if there is even The same situation with emissions I guess on what part of the tag would tell you the mechanic figure it out the California thing with Kari’s car thanks again for your time
So the emissions sticker under the hood says it was built to Canada spec?
I replaced my fuel injectors on my 2000 t4r l after watching your video on that. And my mpg actually went down. Could the o2 sensor be the culprit? I have lifted it and put bigger tires on it since then so my mileage has decreased some more. But before I replace the injectors I was averaging around 19 and after I was only averaging 16 to 17. Also recently I have notice a stumble or hesitation every now and then. Seems to happen under light to medium acceleration and the engine will just seemingly lose power for a second. And it also does it at idle sometimes. Any thoughts?
Where did you get the injectors from?
@@TimmyTheToolman Motorwest performance. The same ones your used in the video
@@sawyerbeals5105 Hard to say what the issue is. Could be a fuel delivery issue. It could be tune-up related like worn spark plugs or a faulty spark plug wire or coil pack. It could be an issue with the throttle body, maybe the throttle position sensor.
Hi Timmy,is there a drive cycle instruction procedure on your manual to reset the catalyst monitor? seems like alot of people are having trouble activating their catalyst monitor sensor after disconecting the batery and there is a debate on how to activate your I/m monitor sensors for a smog check. if you can answer this question and make a video I think it will help a lot of toyota owners and thanks for all the awesome videos you have made.
Francisco Valle if I remember correctly from a recent smog on one of our many 4runners, the procedure to reset the emission systems basically requires you to drive at or above 55 mph for 20-30 minutes. Sean has recently replaced an 02 sensor and took it to the smog shop and they said the system want ready yet and to drive it for 30minutes however we learned later that it’s 20-30 minutes at approximate highway speeds.
I have 4th gen 4runner 2003 model and it consume 19 liter of petrol for 100KM and I have replace almost all the required components like airfilter, spark plugs, cleaned throttle but still poor fuel encomy So the only option is to replace all the four oxygen sensors but the question is: there is no check engine sign on?
So what do u suggest based on your experience???
From what I understand, and I talk about this in the video, an air/fuel or O2 sensor can get lazy but not necessarily throw a failure code. When they get lazy, they might not be sending back accurate info to the ECU to adjust the air fuel mixture optimally. That's the theory. It's the upstream sensors that mostly deal with adjustments to the air/fuel mixture. The downstream ones are just monitoring mostly to verify the effectiveness of the catalytic converters scrubbing the exhaust gases. So, if you're going to replace them, I'd try just the upstream ones and see what happens.
Check your MAF first. It’s usually in or close to the air box where the air filter lives. You can clean it with MAF sensor spray and sometimes, it solves a lot of problems with the air and fuel ratios.
Are these sensors California Compliant? I only ask because when I go to search for oxygen sensors for my 1999, it gives me multiple "Exc. Calif" plugs and a couple that are for "Calif"
mine come up with different part numbers as well.
This is the confusing part and I decided to not worry about it. The Denso website says nothing about California spec or Non-California spec for my 98. I just plugged in my Year, Make, Model and Engine and it spit out all the results. Then, I just chose the right sensor based of my transmission (auto or manual) and whether I had 2wd or 4wd. And, so far so good. No CELs and it appears my gas mileage improved.
It seems the California Spec upstream Air/Fuel Sensors and California Spec O2 Sensors started in 1999.
I had the same problem for my 00. After some research I found out 99and 00 we're the only Cali specific emission models. The 02 sensors also look different. The one Timmy has is for federal emissions. You will see the federal sensor has a million holes while the Cali sensor has 4 holes. If I remember correctly the denso part numbers are...upstream part number is 234-9002( automatic transmission)/ 234-9003(manual transmission) and the downstream is 234-4153." Hope that helps.
@@TimmyTheToolman
..
Thanks for sharing this Colin.
Nice video I need to replace a o2 sensor on 97 4runner limited 4x4 is it the same part number as yours
Glad you like the video. Good luck with the job.
Hi Timmy Great vídeo! The check engine light of my 4runner 96, just turn on, troubleshooting P0420.
1.- Catalytic converter with defects 2.- operation condition o motor fail 3.- vacuum considerable leak. Based in your experience, do you know the probable cause of this code?
Hey Javi, this P0420 code, like many CEL codes can have many different causes. This code pops up due to the downstream O2 sensor picking up a problem with the exhaust gases it's reading. The sensor is saying there's a problem with the Catalytic Converter Efficiency. If it were me, I'd first try replacing the downstream O2 sensor and see where that gets me. Your last resort is actually replacing the catalytic converter(s) because that's lots of money.
@@TimmyTheToolman Hi Timmy, thanks for the advise, did you get the oem o2 sensors from amazon? Other thing, I sent you some pictures vía whats app
Yes, I bought the sensors via Amazon.
On my 2000 Tundra the downstream O2 sensor on passenger side. There isn't a nut on the bottom from the corrosion the top one is corroded so bad I can fit a 10mm socket on it fits to an extent, it's like half a nut holding onto the bolt. What do I do? I can't get it off for anything.n
With that level of corrosion, I think going to a muffler shop might be your best bet and see what they think is the easiest and most affordable fix. With the stud gone on one side, even if you got the other nut off, you won't be able to get the new one properly secured.
Hey Timmy, love your videos. I have a 19 T4R Pro, 16 Tundra, 1986 T4R 22RTE and a 96 T100. I reference your videos for jobs I haven’t done. I recently got the P0171 code on my T100. I replaced the spark plugs and wires back in November, radiator and thermostat in February, transmission flush in March. I’ve cleaned the MAF and just changed both O2 sensors. Should I leave the code on and see if it goes away on its own? That way I can see if it’s something else?
The code won't go away on it's on. The check engine light will stay on until you clear the code. Cleaning the MAF most likely fixed the issue.
Timmy The Toolman I cleared the code after I cleaned the MAF sensor and it came back again when I did that. I’ll clear out the code again now and see what it does. Thanks again!
@@Gunner_0306 Well, hopefully it goes away.
@@TimmyTheToolman it worked. I cleared the code and so far it hasn't came back on. I could tell the the upstream sensor had more black carbon caked on it and is the one that was possibly throwing the code. Thanks again. -Dan
@@Gunner_0306 Good to hear you fixed the problem.
Anybody have the ohm value for testing to see if you have a bad o2 sensor
Hey Timmy,
My check engine light came on giving me a code that my rear 02 sensor was the culprit. Quick look underneath and saw that studs were extremely rusted. Brushed them off with wire brush and sprayed them with PB blaster. First nut came off no problem, second nut came off easily to halfway, and then nut started to really make a screeching sound when I turned nut. I would go back and forth with nut spraying with PB blaster and as I got to the last quarter inch the stud started spinning no matter the direction I turned, and then the stud broke off flush. I put new 02 sensor on with one nut and clamped the other side down with a hose clamp as a temporary fix. I turned over 4Runner to see if I could feel any leaks and discovered about three inches in front of 02 sensor on top of the muffler piping there was a nice size leak.
Then everything started to make sense. My muffler had to be replaced about a year ago and the muffler shop ended up having to weld the forward muffler pipe to the catalytic converter pipe together because they said the flange rusted out. Well the leak I’m experiencing is exactly at the weld on top of the pipe which is located three inches in front of 02 sensor. I remember the mechanic calling me saying I’d probably have to replace my 02 sensor. I thought at the time how the hell did that go bad. While at that time I had no idea what an 02 sensor was so I asked how much and once he gave me the price I said to hold off if the one is still good. He said he could try putting back on but most likely will have to be replaced soon. Well a few weeks go by and sure enough my check engine light comes on. Take my vehicle to a shop and they confirm my 02 sensor was culprit. They reset check engine light code and said it would come back on most likely and sure enough it did.
I then started watching your videos performing maintenance myself saving a ton of money, learning about my vehicle, and slowly acquiring lots of tools. I eventually got my own obd2 reader to monitor my coolant and transmission temp after I installed a cooler as well as used it to check/clear codes specifically the 02 sensor that kept tripping. The only reason I put off replacing 02 sensor for so long is because of all the rust. Anyhow after breaking my stud off I suspect there was no issue with my 02 sensor in the first place and it was the leak in my pipe a few inches ahead of the sensor. Now almost year and half later I am going to call the shop explain the above to them and hope they’ll repair leak in pipe and weld on a stud for a reasonable price considering the circumstances. I am confident that their poor weld job was tripping the 02 sensor code in the first place and they just reset the code before giving my 4Runner back to me.
If shop is not willing to offer a reasonable price I might just order everything ahead of tail pipe and replace it myself. My concern will be removing pipe ahead of the cat because of all the rust! Do you see any other options?
Replacing the exhaust manifold on that side might be your only option if it can't be repaired by the muffler shop. I haven't pulled off the exhaust manifolds off an engine inside an engine compartment yet. The only ones I've removed have been from an engine that was already pulled out from a rig. It might be a little tight getting to all the fasteners but I think you shouldn't have too much problem. I guess the rusty nuts would probably be the biggest concern.
Not what I'm looking for, but I'm looking for a video of replacing the abs censor on 2003 Tacoma front left. Thanks for any help.
We don't have a video for it but its should be pretty easy. The sensor plugs into the knuckle and is secured with a 10mm bolt. You would disconnect it there and then follow the line up until you can find a connection you can disconnect. If it were me, I'd try to find one at a wrecking yard like PicknPull and grab one off a wrecked 1st Gen Tacoma or 3rd Gen 4runner. We do have a video that shows how to disconnect the sensor from the knuckle. In this video, th-cam.com/video/-sY2azyLBuI/w-d-xo.html, go to play time 6:11 and you'll see how we do it.
Did you or have you known anyone had severe problems disconnecting the connection for the air fuel sensor? I was able to remove the rusted bolts but cannot get the cables that rest on top of the transmission visible. I'm beginning to think I will have to lift the body or lower the transmission to get to the connection which seems crazy. Any ideas or pointers?
Hey Shane, I don't understand why you're having trouble disconnecting the air/fuel sensor. The connector you need to disconnect should be visible just like we show in the video.
@@TimmyTheToolman I found the solution in another forum. I have a manual transmission. Apparently they removed the gear shifter and disconnected it from inside. Talk about an obscure find! Going to try it today.
Ah ok. So it sounds like it is on the top of the transmission and they remove the shifter and the boot for easier access from the top. When we did the transmission swap on Sean's rig, some of the connectors are hard to see so you pretty much have to go by feel and find the tab you need to push to disconnect the electrical plug. It's a pain in the ass but it can be done.
Shane Clark I’m having the same problem, I can see the connector I just can’t reach it to plug in the new one, what did you end up doing?
@@hunterwerre I'm going to guess you have a manual transmission like me. It took forever to find the answer. The answer is: go through the cab. Take the gear shift and 4x4 knobs off, remove the trim and then you will see a plate. Unbolt the plate and not your looking at the top of the transmission. You can reach but just barely get to the connection and finish your project.
Hey Tim, I live in the great rustbelt state of NJ and have rusted bolts on my upstream o2 AF sensor. 12mm has morphed into something my tools can't get a grip on. With limited space, any ideas on how I can get these rusted bolts off without damaging the threaded stems?
Thanks, Joe
Maybe some small vice grips would fit.
How can I get rusty nuts off pb blaster and then heat? They are kind of rounded vise grips will work u think?
Yes, heat and penetrant. Vice grips might work. If the studs for the O2 sensor bung are in bad shape, you might have to pay an exhaust shop to weld in a new one for you.
Does the parts above, works with 2wd auto transmission as well?
Go to the Denso Find Your Part website we link in the video description and look up the part numbers. They change based off the year, transmission and whether it's 2wd or 4wd.
Did this increase fuel efficiency?
Most people report better fuel economy after replacing tired O2 sensors even if they didn’t have a CEL on.
@@TimmyTheToolman this is good information. Thank you. I replaced spark plugs, fuel filter, and the upstream and downstream sensor. Haven't been able to drive the distance I have been since but will in a week or so. Average 180 miles to tank, which sparked these repairs. Other deal is what I would consider is excessive heat on the floor of passenger side and center console warming the bottom of my cupholders. This leads me to believe my cat is clogged or partial clogged so that will be next, if I don't notice changes in fuel economy. Thank you sir for all the contributions to the 4runner community, don't know what I would do without your input. Saved me thousands already.
@@keizersoze907 Hey Mark, glad you like the video and you're welcome. Hopefully your mileage improves. As for the heat from the center console, that's most likely just heat coming from the transmission but I guess some radiant heat from the catalytic converter could be affecting it a little bit. Great to hear you've saved a bunch of money doing your own work. Great job and Happy Wrenching!
Are the 2 Denso sensors that you put in the description compatible with a 1999 4runner 3.4L 2WD?
I don't know. You'll have to look it up on the Denso website we provided a link to.
I think one of my friends got changed 212$ to get the part and labor on his 00 Tacoma to change one o2 sensor . I can’t believe it was this easy
Hey Daniel, a lot of auto mechanics is pretty straightforward like this job is and it is surprising how much a shop will charge you for something that takes them 15 minutes to replace. This is one of the reasons why we are trying to empower people to do their own work. The other reasons are it's a good learning experience and a skill you can use over and over again, and then there's the great satisfaction you get when you successfully perform a job. Happy Wrenching!
Hopefully I'll pass the smog check after changing the two 02 sensors
Yeah, fingers crossed it works out for you.
They have the Denson ones on rockauto also
That's cool.
Would this work for my check engine code 25 and 26?
I think you're missing some numbers. CEL codes are usually P with 4 numbers, like P0301.
Excellent explanation of maintenance service, well done!!
Thanks Bill!
Tim my 99 Ltd 4Runner doesn’t have a cat! Looking at the exhaust I noticed someone took it out and deleted it, the computer is throwing no codes. I’m not sure what to do? Would replacing my upstream help anything?
If your upstream is an air/fuel sensor and not just an oxygen sensor, maybe a replacement could help your gas mileage if your current sensor is a bit lazy and not working optimally. I'm guessing you don't live in a state with strict smog laws. Did they delete the downstream sensor as well?
@@TimmyTheToolman no smog in New Hampshire, truck started its life in Arizona then went to Florida. The truck has both sensors still, also is this something that’s ok to go aftermarket vs oem? Much thanks and happy new year
@@johngacy6367 That is very interesting that you're not throwing a CEL code like P0420 - Catalyst Insufficiency. The front O2 sensor takes a reading of the exhaust gases and then after the catalytic converter scrubs the gases some, the rear O2 sensor should have a different reading letting the computer know the converter is doing it's job. The fact you're not getting a CEL code is perplexing. I wonder if that rear sensor is some type of dummy sensor that always shows the air is good.
I would only suggest OEM sensors. I would get the Denso sensors by looking them up in the Denso Find my Part link we provide in the video description. I'm just wondering if you should leave the rear sensor alone. Like I said, I don't understand how you're not throwing a CEL code.
@@TimmyTheToolman maybe a cat delete? I won’t mess with the rear sensor.
@@johngacy6367 OK, good luck with the replacement.
Love seeing your rust free vehicles. A little jealous too:)
Yes, we are spoiled in the California Bay Area.
Go to South Main Auto. That guy works in New York state. I find it unbelievable how much rust can build up every where.
@@Rhaspun same here... it's that liquid Acid they put down here..Everybody leases here! Those of us who like to keep our autos are screwed.
Same
@@tynado1173 I'm re doing my exhaust so i'm going to replace my sensors anyhow. The current one is melted on with rust.
Good video, I have a 0420 code on my 03 tacoma. Have tried sea foam in every way , crakecase, gas, and air intake . The code came back on though, I'm thinking of replacing the up stream o2 sensor, which read 3.00 vts . What you think, thanks for your advise . Kg
If the ohms resistance is out of spec for the O2 sensor, then I'd replace it. I do think a P0420 code would be more of an issue with the downstream sensor. If it's neither the upstream or downstream sensor as the culprit, it may be a situation that you have to replace the catalytic converter. But, if it were me, as a last ditch effort before having to replace a very expensive catalytic converter(s), I'd try a product called Cataclean. It's got mixed reviews but maybe it will work to clean out a partially blocked up catalytic converter and allow the code to go away and you can pass a smog inspection and get your vehicle registered.