I was chasing down a p0171 in both my 2001 Honda Civic and my Dad's 2000 Chevy Prizm (Corolla). The Civic doesn't have a MAF sensor, but I cleaned the MAP sensor and the throttle body, and changed both O2 sensors. Used about 5 different fuel cleaners, and changed the fuel pump and filter. Cleaned the MAF on the Prizm and replaced the O2 sensor. Nothing worked. The same solution, which I have not read anywhere on the net, fixed both cars. I ran a gallon of water through the brake booster vacuum line on a hot car (the car has to be hot to turn the water into steam). Every time I added water, I put the RPMs to like 2000. This is basically like seafoam but you're using plain old water in a much higher dose. Afterwards, take the car for a spirited drive for a couple of miles. My best guess of what is happening is that the intake manifold is getting clogged with carbon over the years. Taking it apart is a pain in the butt, and the hot steam helps clear it out a bit. Worked on both cars. Check engine lights haven't come on since. Hope this helps people.
@@TimmieTennis Unfortunately, the code came back after 200 miles. I changed the MAF sensor and PCV valve but always comes back after 2 days now. Let me know if you figure anything out. People keep saying vacuum leak, but I can't find one. I heard if it's the intake manifold gasket you'd get P0171 AND P0174 because both banks would be lean, not just bank 1. But then again, I heard you only have 1 bank if you have a 4 cylinder, so I'm not sure.
@@aznnp77 I've been reviewing this for a month since I don't drive much and it keeps returning. I've tried two new MAF sensors and had shop look for vac leaks, which wasn't needed since code returns while driving as this vid said. Next things to look at for each of us is O2 sensor and (more likely) injectors. They supposedly can be cleaned, but it sounds like the seals on them go bad and can cause air inlet which causes lean running. I don't want to do it, but the shops are incompetent here, they just throw parts, it's not their money. I paid for diagnosis and was just told 'needs MAF, $500' (they are $75 online, $30 if you like Chinese/knockoffs. Mine is 2000 and I do all my own work.
Excellent video Derreck. I've got a corolla at the shop now with a lean code but no vacuum leaks. This will definitely help. Also, never heard the 1 g/s, per liter, per 500 rpm but that's a great piece of knowledge to have now. Thanks!
Very useful video, you pretty much nailed the P0171... I have the same issue with a 2001 with 210K mikes, still with the original MAF.... after trying to clean it with alcohol, CEL still came on under load going up a hill, so I just ordered a new one.
Same car, same issue, but with a P1305 igniter circuit #2 code as well. Died after startup when warm, bogged down briefly when accelerating, and stalls when running. Cleaned MAF, and got no symptoms for a day or so, then they returned
I have a 01 Toyota Corolla with this code and can’t figure it out changed Crankshaft sensor oxygen sensors Feul pump coil pack MAF sensor spark plugs 🥺🥺🥺
Hello Derreck, Where are you located? Might be worth driving far and wide! As I shop for a mechanic, A mechanic over here said it's usually the intake gasket that needs to be replaced. Is this true? He hasn't seen the car yet was just his hunch to start there $$. I have a 2000 Toyota Corolla with 100k miles - runs great. I have a P0171 too lean bank 1. Thank you for any input or suggestion. Maybe I find someone who has and understands the diagnostics you have first?
I have same code on my 01 corolla i just rebuilt the engine with juat shy of 100 miles on the rebuild im kinda lost looking at live data is there a way u can reach out to me and discuss this maybe look at what my datas showing and give me a direction to troubleshoot.. maf sensor is new and a denso part i did have to reuse the upstream o2 from the donor engine i used for rebuild.. at idle short ft is -20.3 and long is -10.9 maf is reading 0.01 and that measurment is in lb/second o2b1s1 is between .780 and .875 o2b1s2 is .750 and .795
That diagnoser is from Snap-On ? My Corolla VVTi 2000 problem is erratic idle 1200 - 1400 when it should be 700 - 800. Airflow and TPS sensors within spec resistance. New inlet, throttle and idlespeed sensor gaskets. New plugs & radiator cap. Still no cure ! It feels like a vacuum leak somewhere but I don't see any. Ideas ?
@@loganlikeslemons - No one can wait a whole season to sort it out. In the end I took it to my local mechanic. He found the throttle vane was a bit wiggly. He also said this - not vacuum leaks from any point - was the commonest reason for fluctuating idles like mine.
Is it possible that the P0171 on this car could cause the engine to vibrate and shake a lot at idle?? I have checked the motor mounts and I don't think its a misfire because I never have gotten a misfire code....the p0171 has plagued my corolla and I'm worried the engine vibration is a misfire. Can a car be misfiring and no codes get thrown??
I'm no expert, but wrench a lot on my 2000. P0171 is often due to MAF dirty or failing, and this may also cause the vibration since it does act like misfiring/mixture/timing. They are very easy to clean with MAF sensor cleaner only, which probably won't do it, and easy to replace. Get Denso.
Very good, but only a little bit more of what everyone else shows. Hence, I've cleaned my air filter and MAF sensor twice and see no vacuum leaks or tears in intake but CEL keeps returning, after 1-200 miles of me thinking I fixed it. I don't know how to inspect fuel injectors and rtather not just replace them or the fuel pump. I may have a small valve cover gasket leak, but it never registers on my dip stick or driveway. What else?
if it's a dirty Mass air flow sensor it needs to be replaced, when they are working normally they have a self-cleaning feature. the MAF sensor won't throw a code if the self-cleaning feature fails
Hey Derreck I replaced the MAF and both 02 sensors and still having p0171 01 Corolla 1zz engine, this car is absolutely driving me insane, I did check for vacuum leak and I don't have any of that
@@danejurus69 I hadn't heard that either and suspect he means Throttle Position Sensor, which I've not heard for this code, but www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-throttle-position-sensor
my lt trim is at 20 on idle what does that point towards also has a evap code canister is not holding pressure . also numbers dont change when i hold a 2000 rpm in drive they seem to go higher lt trim to 30
Hello Derreck, Where are you located? Might be worth driving far! A mechanic over here said it's usually the intake gasket that needs to be replaced. Is this true? I have a 2000 Toyota Corolla with 100k miles - runs great. P0171 too lean bank 1. Thank you for any input on his suggestion. Seems expensive to start there? @@diagnosticderreck3287
I was chasing down a p0171 in both my 2001 Honda Civic and my Dad's 2000 Chevy Prizm (Corolla). The Civic doesn't have a MAF sensor, but I cleaned the MAP sensor and the throttle body, and changed both O2 sensors. Used about 5 different fuel cleaners, and changed the fuel pump and filter. Cleaned the MAF on the Prizm and replaced the O2 sensor. Nothing worked. The same solution, which I have not read anywhere on the net, fixed both cars. I ran a gallon of water through the brake booster vacuum line on a hot car (the car has to be hot to turn the water into steam). Every time I added water, I put the RPMs to like 2000. This is basically like seafoam but you're using plain old water in a much higher dose. Afterwards, take the car for a spirited drive for a couple of miles. My best guess of what is happening is that the intake manifold is getting clogged with carbon over the years. Taking it apart is a pain in the butt, and the hot steam helps clear it out a bit. Worked on both cars. Check engine lights haven't come on since. Hope this helps people.
aznnp77 thanks aznmp, will try this in the future on my 2001 Corolla....
@@TimmieTennis Unfortunately, the code came back after 200 miles. I changed the MAF sensor and PCV valve but always comes back after 2 days now. Let me know if you figure anything out. People keep saying vacuum leak, but I can't find one. I heard if it's the intake manifold gasket you'd get P0171 AND P0174 because both banks would be lean, not just bank 1. But then again, I heard you only have 1 bank if you have a 4 cylinder, so I'm not sure.
@@aznnp77 I've been reviewing this for a month since I don't drive much and it keeps returning. I've tried two new MAF sensors and had shop look for vac leaks, which wasn't needed since code returns while driving as this vid said. Next things to look at for each of us is O2 sensor and (more likely) injectors. They supposedly can be cleaned, but it sounds like the seals on them go bad and can cause air inlet which causes lean running. I don't want to do it, but the shops are incompetent here, they just throw parts, it's not their money. I paid for diagnosis and was just told 'needs MAF, $500' (they are $75 online, $30 if you like Chinese/knockoffs. Mine is 2000 and I do all my own work.
Excellent video Derreck. I've got a corolla at the shop now with a lean code but no vacuum leaks. This will definitely help. Also, never heard the 1 g/s, per liter, per 500 rpm but that's a great piece of knowledge to have now. Thanks!
You're welcome. Just remember that rule only works at idle. It does not work if you are giving it any throttle!
Very useful video, you pretty much nailed the P0171... I have the same issue with a 2001 with 210K mikes, still with the original MAF.... after trying to clean it with alcohol, CEL still came on under load going up a hill, so I just ordered a new one.
Did getting a new MAF solve the issue?
@@danejurus69 Yes, a new MAF fixed it, no more CEL...! The original lasted 18 years!
Hi I was wondering how did you clean the MAF sensor
Same car, same issue, but with a P1305 igniter circuit #2 code as well. Died after startup when warm, bogged down briefly when accelerating, and stalls when running. Cleaned MAF, and got no symptoms for a day or so, then they returned
I have a 01 Toyota Corolla with this code and can’t figure it out changed Crankshaft sensor oxygen sensors Feul pump coil pack MAF sensor spark plugs 🥺🥺🥺
Did you solve ?
Yes I did figure it out thanks
What was the issue?@@johnquinones4671
For P0171 code can O2 sensors or worn out catalytic converters cause the code to show ?
Hello Derreck, Where are you located? Might be worth driving far and wide! As I shop for a mechanic, A mechanic over here said it's usually the intake gasket that needs to be replaced. Is this true? He hasn't seen the car yet was just his hunch to start there $$. I have a 2000 Toyota Corolla with 100k miles - runs great. I have a P0171 too lean bank 1. Thank you for any input or suggestion. Maybe I find someone who has and understands the diagnostics you have first?
I have same code on my 01 corolla i just rebuilt the engine with juat shy of 100 miles on the rebuild im kinda lost looking at live data is there a way u can reach out to me and discuss this maybe look at what my datas showing and give me a direction to troubleshoot.. maf sensor is new and a denso part i did have to reuse the upstream o2 from the donor engine i used for rebuild.. at idle short ft is -20.3 and long is -10.9 maf is reading 0.01 and that measurment is in lb/second o2b1s1 is between .780 and .875 o2b1s2 is .750 and .795
That diagnoser is from Snap-On ? My Corolla VVTi 2000 problem is erratic idle 1200 - 1400 when it should be 700 - 800. Airflow and TPS sensors within spec resistance. New inlet, throttle and idlespeed sensor gaskets. New plugs & radiator cap. Still no cure ! It feels like a vacuum leak somewhere but I don't see any. Ideas ?
If it has high idle in the summer and low idle in winter chances are it's your intake manifold gasket
@@loganlikeslemons - No one can wait a whole season to sort it out. In the end I took it to my local mechanic. He found the throttle vane was a bit wiggly. He also said this - not vacuum leaks from any point - was the commonest reason for fluctuating idles like mine.
you can find vacuum leaks with a smoke generator
Great video Derreck. Thank you for posting. Very helpful.
Love your video’s bro. Send my love and respect
Is it possible that the P0171 on this car could cause the engine to vibrate and shake a lot at idle?? I have checked the motor mounts and I don't think its a misfire because I never have gotten a misfire code....the p0171 has plagued my corolla and I'm worried the engine vibration is a misfire. Can a car be misfiring and no codes get thrown??
I'm no expert, but wrench a lot on my 2000. P0171 is often due to MAF dirty or failing, and this may also cause the vibration since it does act like misfiring/mixture/timing. They are very easy to clean with MAF sensor cleaner only, which probably won't do it, and easy to replace. Get Denso.
Very good, but only a little bit more of what everyone else shows. Hence, I've cleaned my air filter and MAF sensor twice and see no vacuum leaks or tears in intake but CEL keeps returning, after 1-200 miles of me thinking I fixed it. I don't know how to inspect fuel injectors and rtather not just replace them or the fuel pump. I may have a small valve cover gasket leak, but it never registers on my dip stick or driveway. What else?
if it's a dirty Mass air flow sensor it needs to be replaced, when they are working normally they have a self-cleaning feature. the MAF sensor won't throw a code if the self-cleaning feature fails
Hey Derreck I replaced the MAF and both 02 sensors and still having p0171 01 Corolla 1zz engine, this car is absolutely driving me insane, I did check for vacuum leak and I don't have any of that
Mike Zaldivar clean tps
What is tps?
@@jabao9492 what is TPS I T PLS can you explain so we know ,,, Thank you
@@danejurus69 I hadn't heard that either and suspect he means Throttle Position Sensor, which I've not heard for this code, but www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-throttle-position-sensor
man o man the hardest code to fix. only on yourybe it's always a cracked intake boot or bad MAF.
Holy crap! I'm just going to sell my car than get involved with this sh*t!
Great video. Lots of good info. I'm definitely going to subscribe.
my lt trim is at 20 on idle what does that point towards also has a evap code canister is not holding pressure . also numbers dont change when i hold a 2000 rpm in drive they seem to go higher lt trim to 30
That was an awesome video great job
Did the CEL go away? Are you sure this fixed it?
Pleade correct me if am wrong!
Thanks
How much do you charge for something like that?
A job like this generally bills out at 1 hour labor. Shop labor rates vary a lot by location, anywhere from $60 to $150 an hour.
Hello Derreck, Where are you located? Might be worth driving far! A mechanic over here said it's usually the intake gasket that needs to be replaced. Is this true? I have a 2000 Toyota Corolla with 100k miles - runs great. P0171 too lean bank 1. Thank you for any input on his suggestion. Seems expensive to start there? @@diagnosticderreck3287