Tacoma: Check engine light - Code P0171

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Thread: Tacoma: Check engine light - Code P0171

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    Default Check engine light - Code P0171

    On my 99 Tacoma (V6 with 40k miles), I've had a check engine light coming on and off. It's on at the moment, ran it by Autozone, and they pulled a P0171 code.

    Noticed in Lon's garage that a 171 can be:
    - air induction system
    - injector blockage
    - Mass Air Flow meter
    - engine coolant temp sensor
    - Heated oxygen sensor (bank 1, 2 sensor 1)

    Before I proceed with replacing the oxygen sensor, should I replaced the Mass Air Flow meter? Exactly where is this sensor located, and what does it look like?

    TIA!

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    Default P0171 Issue

    I have had my engine light go go and off for about 20k and up until today the dealers haven't been any help. I should have pressed the issue earlier. But I just rolled 60k on my '02 (with the K&N air filter system) and the damned light came on again. This time the mechanic at the dealer said it was the P0171 code which meant it could be the K&N tube intake as it had a design flaw. They traded my old tube for the new one which has a restriction before the MAF which supposedly reduces the volume of air flowing over the sensor. They said that works most of the time. However, after hooking it up to the computer he said it really was the MAF because the sensor was still sending the "Too Lean" signal. So I'm going to try the MAF and I'll let you know how it goes. $115 bucks and a prayer.

    BTW the MAF sensor is a rectangular plug that is attached to the air intake by two screws at opposite corners of the sensor. It is about 1x2 inches and has a wiring plug attached to it and should be visible as soon as you lift the hood. Try your best to keep it as clean as possible. Good luck and let me know what you find out.

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    Default

    before you replace the maf, try cleaning it with a cotton swab and some rubbing alcohol.

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    Default Thanks!

    Didn't have the time to service this one myself, dealer took care of it and it turned out to be the MAF.

    Appreciate the help anyway.

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    Default MAF Gasket?

    I have the new MAF from Toyota but the new part doesn't have a gasket like the original part. Other than that they are identical. What gives? The dealer says there is no gasket on the replacement part due to it being manf. in US, but the part looks exactly like the original including the "Hitachi". I am a bit skeptical about the knowledge of the dealer (which seems a bit odd). He recommended silicone. Are there any suggestions as to what I should use?

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    The MAF sensor has an "o" ring, but since your running the K&N kit they have a gasket, so you'll have to contact K&N for a replacement.

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    Default p0171 and k&n

    Hi there guys,
    for all of you getting the p0171 code and have a K&n filter just like the previous person said clean the maf with either cotton swabs and alcohol or spray brake cleaner (one that wont leave a residue) into the maf. The oil from the filter is coming off and sticking to the hot wire inside the maf and throwing off the maf. Give this a shot before throwing your money away on a new maf. This also applies even if you dont have a k&n but there is a leak after the filter dirt will build up on the wire.

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    Default Cleaning MAF

    I already purchased a new MAF before trying to clean the old one, but out of curiosity I decided to try the alcohol and cotton swab. It worked and was easy, you just have to be careful because the wires are pretty thin and fragile. My mileage imprved about 2 mpg on the highway (about the same in town). Thanks for all the help. I guess I have a spare for when my old MAF finally does crap out.

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    Thumbs up SurfRatCC

    Quote Originally Posted by usmc grunt
    I have had my engine light go go and off for about 20k and up until today the dealers haven't been any help. I should have pressed the issue earlier. But I just rolled 60k on my '02 (with the K&N air filter system) and the damned light came on again. This time the mechanic at the dealer said it was the P0171 code which meant it could be the K&N tube intake as it had a design flaw. They traded my old tube for the new one which has a restriction before the MAF which supposedly reduces the volume of air flowing over the sensor. They said that works most of the time. However, after hooking it up to the computer he said it really was the MAF because the sensor was still sending the "Too Lean" signal. So I'm going to try the MAF and I'll let you know how it goes. $115 bucks and a prayer.

    BTW the MAF sensor is a rectangular plug that is attached to the air intake by two screws at opposite corners of the sensor. It is about 1x2 inches and has a wiring plug attached to it and should be visible as soon as you lift the hood. Try your best to keep it as clean as possible. Good luck and let me know what you find out.
    Hello everyone-
    New guy on the block with what sounds like is a similar problem. I have a 2001 DoubleCab Tacoma/TRD. Put in a K&N air filter about 7 months ago and instantly saw a difference. I dusted a few Mustangs off the line myself. Here is my question. Recently got a check engine light myself and took it in. Tech tells me it is the Fuel/Oxygen sensor and it needs to be replaced. Talking with my neighbor(a Tundra owner) -- says this is characteristic and that I could get on the site and find a "How to" with parts #s and so forth. That is what I am looking for. Any information or direction would be super cool!! SurfRatCC

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    Default O2 Sensor?

    My Yota Master at the dealership said my error was an O2 sensor error. I had my O2 sensor replaced and the light stayed off for about three weeks. Then it came back on. I checked the paperwork for the O2 sensor replacement and it indicated code P0171 (evidently a Mass Air Flow sensor error, not an O2 sensor error). Thats when I started asking questions on this forum.

    Toyota did give me a replacement K&N Intake Tube (I originally purchased my filter system at the dealership) and swabbed my MAF wires with an aloholic Q-tip. Everythings been great so far (about three months without an issue).

    Good luck!

    Praise God and pass the ammo!

    USMC Grunt

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    Default O2 Sensor

    Quote Originally Posted by usmc grunt
    My Yota Master at the dealership said my error was an O2 sensor error. I had my O2 sensor replaced and the light stayed off for about three weeks. Then it came back on. I checked the paperwork for the O2 sensor replacement and it indicated code P0171 (evidently a Mass Air Flow sensor error, not an O2 sensor error). Thats when I started asking questions on this forum.

    Toyota did give me a replacement K&N Intake Tube (I originally purchased my filter system at the dealership) and swabbed my MAF wires with an aloholic Q-tip. Everythings been great so far (about three months without an issue).

    Good luck!

    Praise God and pass the ammo!

    USMC Grunt
    Thanks for the info and quick response. I completely agree with your quote. My dad was 31 years military!!! Sempr Fi
    Later

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