Diagnosing a catalyst efficiency code (P0420 or P0430)
ฝัง
- เผยแพร่เมื่อ 12 มิ.ย. 2013
- Uh oh, it’s the dreaded P0420 (or P0430)… This Ford Taurus gave me the opportunity to discuss catalytic converter testing, as well as a chance to demonstrate an oxygen storage test. There’s a lot of misinformation in the industry about converter efficiency codes, and I’m hoping to clear up a lot of that with this case study. To be clear, this video is addressing catalyst efficiency codes ONLY, not restricted exhaust problems!
Engine Performance Diagnostics chapter 5 pages 24 - 27
Symptoms
- check engine light (P0420, P1000, P1270)
Fix
- replaced the failed catalytic converters
Tests shown
- understanding the significance of the P1000 code and how to inform your customer
- understanding how catalyst temperature is important to catalytic converter diagnostics
- using exhaust gas to heat catalysts for testing purposes
- checking for other potential faults such as faulty O2’s and exhaust leaks
- performing an oxygen storage test using propane enrichment
- using a scope to view multiple O2 sensor signals
- how O2 signals can look good but still fail a catalyst monitor
- detecting a borderline catalytic converter
- checking for external sources of catalyst failure, such as misfires and fuel trim issues
- understanding the distinction between a plugged catalyst and an inefficient catalyst
Tools used
- Autel MS905 MaxiSys Mini Diagnostic System with Connector Kit - USA Version
www.jbtoolsales.com/autel-ms9...
- OTC 7148 Propane Enrichment Kit
www.jbtoolsales.com/otc-7148-...
- PicoScope 4425 4 Channel Standard Diagnostic Kit
www.aeswave.com/PicoScope-4425...
Playlist
- (Chapters 4 and 5) Fuel Trim and Oxygen Sensor Testing
• (Chapters 4 and 5) Fue...
Related videos
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• O2 sensor testing (fix...
- P0133 O2 Slow Response (reversed O2 connectors) - Hyundai
• P0133 O2 Slow Response...
- How to test an oxygen sensor on a Honda (scope vs voltmeter)
• How to test an oxygen ...
- Downstream Fuel Trim (A James Danner video review)
• Downstream Fuel Trim (...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC. - ยานยนต์และพาหนะ
Finally, someone who knows what the hell they’re talking about. This video is a true diamond in the rough. So much BS associated with the P0420 code. Thanks a ton for taking the time to make a quality, informed video
Thanks so much!
Seriously. This video clears up so much of the mystery in regards to Cat inefficiency DTCs. It makes sense now why the spark plug extensions hack works to temporarily trick the ECM into thinking the cat is fine. Pulling the sensor out of the stream and reducing the amount of gas it's exposed to emulates the lower O2 value the ECM is expecting. Note to nerds like ScannerDanner, be sure to tell the hillbilly why it works so we can limit the amount of backwoods magic they push. JK... Nice content!
@@ScannerDannernew to the concept of scopes... possible explain how you choose to connect leads?
@@johnharbour633 a lap scope is nothing more than a very fast voltmeter, you would connect a scope to get a signal the exact way you would connect a voltmeter to get a signal. One lead to the wire you are testing and the other lead to battery ground
@@ScannerDanner I really need you me help telling me if this means when it jumps (usually) is it clogged or just failing?? Like if it is still flowing it has no effect on performance so it doesn’t mTter to me but if it’s clogged that is performance issues???
Extremely thorough, and I am grateful for it! Thank you for enriching my troubleshooting tactics.
You are an expert in teaching theology step by step so that anyone could fully understand the concepts of automotive to do most any repair given the aptitude of the individual! I totally commend you for that! Thank You!
Thank you Ronald
There is a lot to learn in each of your videos. You are a good person. You share your experience with us.
Fantastic video. Helped me tremendously to diagnose a P0420 code to make certain that the converter was actually bad. Thanks for a really informative video.
Thanks SD you have one of the most informative channels on TH-cam !
I've watched alot videos the last few days, working to making sure the cat is my issue. Even bought an "entry" level scan tool. This is by the far the best explained and informative video I've found. Thanks for helping a handy guy like me, play mechanic when I have to. 🙄
Six and half years later, still relevant and helpful! Thank you @ScannerDanner!
One difference now is that many upstream sensors are air fuel rato (AF) sensors which produce different graph readings. So comparing waveforms from an upstream sensor to a downstream sensor doesnt work. The point being be sure if you are dealing with an upstream O2 or AF sensor. The emissions sticker under the hood will tell you.
Paul, I can't tell you how many times I've learned something from your videos over the many years ive been watching. Thank you so much for taking the time to make these videos. These are priceless for new techs showing them the theory of how modern vehicles work. Cheers brother 🍻
Thanks man. Some of the material is timeless and is just as relevant today. Appreciate your comments
Thanks for the reminder about Mode 6. I rarely use it and should more often
Any other UTI Technician learning more from this channel than the classes ever taught 😂
I just finished section 4 & 5 in your book so this video was posted just in time! Thanks Paul
A very knowledgable teacher, thanks
I absolutely appreciate your dedication to create better technicians. It's time to sign up and get saturated by all your material again. It really makes all the difference. I made major strides in my career as a result of using this advanced training.
Thank you Mike! Looking forward to hearing from you in the comments section of the classes
I came across this video while researching my nissan 0420 code. Great info. Great video. Thanks for sharing!
Awesome video. I've got a vehicle coming in this afternoon. An MOT station has told him his car has only just passed emissions and he needs a cat. I cannot wait to test it now! Thankyou
Wish i lived in PA. I could probably pass ur class jus from the amount of time spent the last 8 months on ur videos. As always. Thanx again man
very informative video, love the content, successfully help me to determine which o2 sensor was failing on my car and also help me save some money, thanks mate
Great info used this info to fix bad cat on 05 Ford Taurus had down stream o2 stuck lean watched video again and found the bad sensor thanks Mr danner
Ughhh the dreaded P0420. My wifes 2001 Subaru Outback, 3.0L six cylinder, 190K miles started to throw this code now and again for several months. Well tuned engine, no exhaust or intake leaks. Engine was running good. I removed and thoroughly cleaned the inside of the original PVC valve and added a high quality fuel injection cleaner in the gas tank. I cleared the code. It has been 6 months now, NO problem. Most 420 codes do mean a cat replacement is necessary but not always. Great video!
Thank you Michael for your input.
Thanks man. Most valuable video there is on the topic. Wish I'd watched it first. The shorter vids I watched taught me just enough to be dangerous. You really went over a lot of variables that are important. Thorough as can be. Thanks again.
Thank you!
Thank you for the graphics showing the results of both the good and bad catalytic converter oxygen sensor readings!!
This is gold. I have been struggling with my accord and trying to understand these things and this made it so easy. Will download that ebook. That’s a price to pay to learn and understand what’s going on vs spending hundreds to a mechanic who will do trial and error and still have the code...
Trial and error certainly is not the troubleshooting I teach. Thank you very much!
How goes it Scanner Danner! Just wanna say thanks so much for taking the time, initiative and having the care to make and post these videos! I have been working on a car with all the symptoms this one had and just learning to read scan tools and the graphs on one and I'm hooked! I have never looked at computer diagnostics this way and frankly I'm fascinated now and want to learn all I can bout them! I'm almost certain at this point given my data and after seeing this video( not to mention the chunk of ceramic honeycomb that blew out tailpipe on test drive[good thing I stopped to see what noise was])I most definitely have bad cats and probably caused from dead O2. I'm headed over to your website now! Please keep up your channel and fine job thus far! You're a fantastic teacher!
Been binge watching your videos again.
We had huge problems here in Oz with the Holden Commodore (US Pontiac GTO I think), with the early LS series engines throwing P0420 and P0430 codes, GM Holden must have made hundreds of thousands of dollars, if not millions on replacement convertors, which, came with replacement exhaust flange gaskets.
After the first two or three I saw with the fault I decided to do a bit more testing, smoke tested the exhaust, with engine not running, no leaks, smoke tested the engine whilst turning it over by hand, exhaust pipes plugged, no leaks. Finally flooded the engine running with the smoke tester, with UV dye added to the smoke oil.
I discovered UV dye staining around the donut style flange gaskets, the leak would only occur with the engine running, the problem was the gaskets would go hard with age and then leak when engine vibration was a factor.
GM Holden made a massive amount of money selling new convertors when the fix really was the new gaskets that came with the new convertors.
After the initial testing we made hundreds of fixes to customer's vehicles by replacing gaskets only. Moral of the story... test, don't guess.
Hey Jake. Great write up. I’m in Australia too and see these codes quite often. Very interesting. Where in Australia are you?
@@DanWallis86 Perth mate
Me too. Are you on Facebook? Can I send you a message on there?
@@DanWallis86 not on FB.
@@1977jelliott no worries. I like your write up you did on the exhaust leak. Thinking outside the box a bit.
I’m in a few mechanic groups on Facebook and a mate of mine has a shop in gnangara. We have been trying to organise a couple of training nights for local mechanics to learn about pulse sensors and scope use. Would be good to get people who like to take a somewhat different approach to repairs rather than just firing the parts cannon.
Excellent Sir! I bought my 2006 Chrysler 300 in 2005. Check engine light came on within a month. It ran rough for a while and eventually started back running like a sewing machine, as it does today, still. The light stayed on though. I kept procasting and failed to take it back to dealer for repair while under warranty. When you said a converter can be bad while a car runs smooth, it made perfect sense, especially since the reputable car repair shop replaced OEM oxygen sensors after the p0240 code came up, showing they needed replaced. The light is back on after 53 miles with the same stored (not active code) I am now convinced that the converter is bad and will by one from the dealer and have it installed. I hope this will take of the problem once and for all.
Well I ran into this today. Wife's car throwing a p0420 (2011 Nissan Altima S 2.5) Checked for leaks, checked sensors, checked fuel trims, and honestly I was a little lost. Then I got and idea💡 search for some scanner danner p0420 trouble shooting videos, came across this one which just stepped my game up when it comes to confirming a bad cat. Ran a propane enrichment test BINGO bad cat. Man I love these videos. Before I can say and admit I was a parts changer but now I have learned the error of my ways watching many MANY of these videos by Mr. Danner. Thanks again for all the great you do my good sir!
Thanks so much!
I think you are an expert! You are humble. 😊
Great effort, and greater information. Thank you a million for your time.
another great video, very informative. you're one of the best. thanks Scanner Danner!
He's already denied being a god.
Great info. Great instructor. Great video!
Great stuff man, that propane test is on point 👌🏼
i love how informative this video was, I already knew this but i wanted to super make sure this how it actually works.
You’re no parts chaser. Well explained and thoughtful. Thanks.
This brings more light to my old schooling.
Thanks, Paul! Fantastic education on what we can look at to understand cat status. Diagnostics over parts cannon. Because of this vid I found ForScan available for my ‘05 Ford Escape 3.0L, and well worth the price of a dedicated OBDII connector with Ethernet cable. I can now evaluate these same values and graphs, which has alleviated my concern about the front two cats (had to replace the rear, which crapped out not long after repairing the famous Ford Escape ignition coil problem causing misfires). So much more confident in monitoring things myself now.
Excellent information! Very thorough, very useful!
Thank you for the info, it helped me read my maxicom mk808. Now I know what I'm looking at.
scanner danner you are the best iv learned a lot watching your videos thank very much
Wished you did bonus footage of the propane test after repair.
Good point Steve. Thank you!
This is one of the best videos I've seen on TH-cam. Now. I just need money for an expensive scan tool. I bought the $44 one now. I'm like damn it.
Harbor freight $75 Zurich zr8
Wow, super informative video. Thanks for putting it together. I learned a ton!
Thanks for watching!
Very Nice.. Paul. You always stand outstanding..
I like this video. I had some issues with troubleshooting catalytic converters. With my scanner I can see in frame data oxygen sensors mV and buy looking them I determine is the catalytic converter good or bad, but I can not be 100% sure. I do not have graph mode so I am relining on numbers I see. Now, I will do more measurements with scope as in this video. It is very important to tell to the customer in 100% that converter is good or bad...not just to assuming.Great video Paul.Thanks so much.
Excellent. More 'tools' available in the bag. Nice job.
That's was a GREAT DETAILED INFORMATION ... Big thanks
Really it's the best and perfect explanation i have ever seen,,,, thanks man ,,,translate this quote and mention the speaker ( الهندسة كما يجب ان تكون )
Thank you for this video, I finally understand how the sensor values work and what they mean. Now I can diagnose my sisters P0420 ^~^
Mr. Danner! Just want to say thank you for taking the time to make these videos. I need to buy your book. I’ve learned a lot from you, and have become a lot more confident in my diagnostics since I started watching. One quick question. Could you do this propane enrichment test with acetylene or MAP gas? I don’t have any propane at my shop.
Excellent explanation on catalytic converters 👌
picked up a lot of good info in this video Paul, i too have had issues with aftermarket cats not to the same standard as the oem mainly with the Ford focus here in the uk
Excellent stuff, well explained
Thanks Paul, awesome as always !!
Great quick test info!
How much propane are you introducing? Do you just keep injecting more propane until the short term fuel trims respond with a full rich signal? You are the master of the scanner; love to watch you work. You capture the info on the video quite well. The extra effort shows.
I have a 2001 taurus it was throwing the PO420 code as well, plus gas mileage was down. Changed all 4 O2 sensors. Dumped a bottle of cat cleaning solution in it at 1/4 tank drove like 45 minutes. Cleared codes. And the PO420 code popped back up. Got online and googled the PO420 codes it said check O2 sensors which I replaced all 4, check ECS (engine coolant sensor) sensor. I scanned it it was running at 174 going highway speed until I slowed down then it would go up to 185-190. So I decided to change the ECS sensor to see what it would do after clearing the codes again. And the PO420 code hasn't popped up since then and the temp has been at 185-190 since and my gas mileage went back up too. And it's been a week since changing the ECS sensor. So I'm guessing it was ECS all along with the PO420 code and not the cat's or the O2 sensors. Thank god I didn't replace my cat's w/o changing my ECS sensor first. I do cheap parts first b4 going to the most expensive parts. Sorry for the long story lol.
i had a car with a p0420 code diagnosing. It wasnt the cat or oxygen sensors, but the problem was a faulty intermittent crankshaft sensor !
Excellent job, and explanation.
Awesome video. Thank you for sharing your knowledge. ⭐️⭐️⭐️⭐️⭐️
Great info, My friends 2011 Arcadia has po420&30 codes still with all new o2s and cats. When I heard it wasn't fixed I scanned the SUV and found the downstream o2s almost mirror the upstream sensors. He said they put in OEM parts.??? Now I've got some direction to go after S & L trims all looked good. It runs great and no other values out of range. O2s all respond correctly to rich lean commands. I'll check common components to both banks like PVC, leaks intake or exhaust, and them run the o2 retention test. Thanks! Oh forgot GM TSB PIP5232A states check engine block grounds on vehicles 2015 and older if you have cat failures. I find that interesting.
Did they use OEM cats? I doubt it as they're 3 or 4 times the cost of aftermarket.
Unfortunately that is what is needed on these! Factory cats only!
It will depend on the com protocol as well as the scanner used and how many data PIDS you are displaying at once. So it is not set and cannot be relied upon for a time base. Unless you has a run time data pid to compare next to and some cars do provide that PID
Good tutorial video,on graphics views,thanks Danner
Thank you for creating this video!
Hey Dan, good video thanks. I get the p0420 code often on Subaru's in NZ, this video is helpful. What differences would you get using a gas analyser when doing this test? when doing MOT tests back in Scotland we did a catalyst stability test, we found any faulty cat would read high on co. We also found any running issue would show high hydrocarbon level. If all else showed good but lambda was out the most likely thing was up stream o2 sensor. What are your thoughts on this? Thanks
This video helped me out today. Thank you younger 7 years ago scanner danner
lol nice
Awesome! I just had a car (same make and model as this one,) in the shop with the same code. I did the same upstream/downstream O2 comparison and found on bank one the frequency and amplitude were identical. I also did the inlet and outlet temp test and it really wasn't conclusive like you said it wasn't. I didn't know about the oxygen storage test, thanks so much for another test to put in my repertoire!
Thank's! Great video!
Good write-up/ video.. And customers wonder why they are paying 120 per hr + to diag their car.... Also I had a 2018 suburban I installed an aftermarket cat on and it threw code as well for it.. rechecked data and it wasn't enough oxygen storage.. so I installed a FACTORY GM cat and all was good after that...
Nice thanks for your master explanations. hope when you have a chance to make a study case for P420 and P0422 on Nissan Maxima from 2002 to 2007.
I have been gathering O2 storage numbers off known good cars lately, I am seeing 2-4 seconds on average as well.
during your tests the o2s22 seemed to be lean at 200mv. thought at or around idle should be around 400 to 600 mv ??? is this normal ?? or what should the o2s2 read. thanks Paul for great videos !
Thanks very explainable and good tips
Excellent video well explained
Hey Paul, I know this is an old video and I've watched it before, but I'm wondering how this test would look/work on a wideband/Lambda system (I work on Benz). If the vehicle is equipped with 6 and 4 wire wideband Lambda sensors (specifically 6 on the upstream and 4 on the down) could you still do the O2 storage test with a scope, and how would that work/look? Do you have any videos doing this test on that system?
Thanks again for all that you do!
good job paul keep them coming
I don't plan on making any major changes. some additional hyperlinks added for quick reference to my youtube videos maybe. but these can be found in my playlists I have recently created for each Section in my book.
So you are good to go with the paper version if you like.
Any brand new material, say a new chapter on GDI would NOT be added to either the eBook or paper book. It would be separate. (We are talking a few years away from now before that happens, I need my own case studies first)
Awesome video..I've got a 2008 Dodge Challenger SRT 8 that keeps throwing a check engine light. First it just came on, and this last time the check Engine light was blinking off and on and the car was running very rough. So I took it back to the dealership. They said they replaced all 4 O-2 sensors. They drove it, and it came back on. Same code as begore. It said Fuel trim issue, lean bank 1. They are telling me that the computer is reading the codes like the catalytic converters aren't working up to Federal standards for emmissions. Needless to say, they've had my car for two weeks and can't figure it out. Do you have any idea what it could be?
@@leemassey9065 a blinking light is a misfire code and rough running suggests a misfire too, it is not the cats, take it to someone who know how to troubleshoot
Hello, Sir. I have been a big fan of yours for years now. Always looking forward to your new videos. In the video, you mentioned exhaust leak before the cat. Would that cause a p0420 or P0430 code? A little explanation would be very appreciated!
Yes it would!
Thanks for the great video!
So now some years have passed and you have done the test on more cars and how many seconds delay does a good cat cause of the downstream O2 ?
@19:35, looking at the graphs, i can see where you were leaning too far and missed the hole with the propane ha ha. Thats the dip in the middle of the signal. :D. Just trolling a bit. Good vid as always.
I guess this test could be influenced by tired O2 sensors. Is it possible that the bank 2 cat is just as bad as bank 1 but the downstream sensor is also worn out and responds very slowly?
nice video it support you eBook cat testing chart,
Paul what test method will be better to apply when I have a/f sensor on upstream? , at this point I can not compare upstream and down stream , thank you very much for this upload.
nice work!
Great info, Thanks for all your videos, I feel like I'm always learning something new from your videos! Does service info ever give a time frame for the oxygen storage test?
not that I am aware of my friend
VERY informative. I had known previously it wasn't a good idea to just get to replacing cats but I wasn't quite aware of what the variables were although I suspected they existed. I never heard of the oxygen storage test before. Thanks for the awesome video!
Hey Paul, what of valve do you have at the end of your propane bottle? I tried doing the oxygen retention test, but I was not successful due to the fact that I was using a soldering torch to feed the propane into the intake, but it never got the engine to run off of the propane. Please share where you got it or tell me if I did something wrong. Thank you.
You are right about using a factory cat. I was talking to a sales rep for an aftermarket cat company and they told me that their cats did not flow the same airflow as the factory's flow.
IT is not a flow thing. It is a precious metal thing. The factory cats are using either more of those metals or different types that are more effective. There is a reason that aftermarket cats are not worth much to a salvage yard compared to a factory one.
great video! Thank you!
All I'm getting on an '09 2.4L Toyo Camry is this lone P0420 code. Sensors were all replaced a 2 months before the CEL even came on. Going to try some fuel additives, maybe even inject water/ammonia to steam clean. Too bad located an exhaust leak isn't as easy as finding an intake leak.
Best explanation video for cat efficiency codes I’ve seen. I’m getting good oxygen sensor behavior but yet throwing cat below threshold codes on both banks with brand new cats…I can’t bring myself to risk it and throw factory cats in if it’s not going to solve the problem 😬😬 2007 tahoe 5.3
Factory cats unfortunately my friend
Or an anti-fouler in the rear O2s 🤫
@@ScannerDanner I put them in both rears today haha we will see 🤞🤞
@@nathanielmoore5677 did it work?
Another great video.
Good info, thanks Paul.
A question, can i perform the same test using the Torque pro app on my Android phone? (i'm new to the Torque app. so far i just use it to retrieve fault codes. I know i barely scratch the surface on this app).
I've gotten a P0420 fault on my 99 Civic EX.
Great video.
Would these graphs apply the same way to air/fuel ratio sensors?
Another great video Paul, thanks.
I recently had a P0420 code on a Nissan Primera P12 QR20DE. The oxygen storage test gave a .3sec (300m/sec) delay. Because of the high cost of a new cat I told the owner I could borrow a 2nd hand one and test for the difference. That cat increased the delay to .65sec (650m/sec), way short of the 2 sec I was hoping for but the code has not returned and the customer was very happy (she even did some baking for us).
We here in New Zealand don't have emissions testing (yet) but do you think a cat like this would pass some of the more stringent emissions testing as done in California for example.
This car was bought new in New Zealand but built up in the UK and I wondered if it was possible we could be supplied cheaper/low quality cat's due to our lack of testing.
The most brilliant mind to ever do the dam thing, the brother too is impressive. Would give anything to be a fly in the wall at that shop for a day.
Great video thank you.
Hey Paul,
Great video, i just fixed a P0420 on a 4cyl Barina, turned out the cat was blocked up (full of carbon deposits), the car LTFT was at -30% and the car was bogging down on load, in this instance i did only a back pressure test to give me direction, i will try using this method if i get the chance.
Hi Paul,does this test in any way relate to the CO removal(or conversion)of the cat or is this something that can only be tested with a CO machine ?.....Many Thanks 👍🏻
... Priceless
Mine shows P0420 and P0326. 2007 Hyundai Entourage, 205k miles. engine reportedly was replaced @ 38k. The only time the downstream mimics upstream is after idling for several minutes, bring RPM to 2k readings normal, and remain after return to idle. after about 7 to 10 minutes symptoms begin to reappear. Am about to attempt propane test using lab scope, have not tested KS, yet.