1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

check engine light on

Discussion in 'Chevy Trucks' started by ABES, Sep 9, 2007.

  1. ABES

    ABES PlowSite.com Addict
    from MN
    Messages: 1,322

    so heres the deal my 99 chevy K2500 OBS 350 V8 has the check engine light going off and on. the code is system too lean bank 1. it will come on for a week or so then it will be off for a month or more. it just came on today and it hasnt been on since july. the only thing i have noticed is it pings when i start it up when its cold. i tried cleaning the mass air flow sensor and it didnt help. im wondering what else the problem could be. anybody else have this problem

    thanks
     
  2. mrmagnum

    mrmagnum Senior Member
    Messages: 162

    It sounds like you may have a faulty oxygen sensor. Does it say "bank 1 sensor 1 or bank one sensor 2" or does it just say bank1? Many vehicles have more than one sensor on the bank 1. With out being able to check it in person it's hard to say but the oxygen sensor is probably a good starting point.
     
  3. ABES

    ABES PlowSite.com Addict
    from MN
    Messages: 1,322

    p0171 is the code again its "sytem too lean bank 1". it doesnt say anything about an oxygen sensor so i have no idea what it could be.
     
  4. mrmagnum

    mrmagnum Senior Member
    Messages: 162

    The oxygen sensors tell the computer if the system is too lean or too rich.:)
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Before you spend $100 on an O2 sensor you may not need, first check for an exhaust leak between the manifold and the cylinder head on the driver side (this is the "bank 1" side). With an exhaust leak, it will allow extra oxygen to enter the exhaust ahead of the O2 sensor which will cause the ECM to think that the left bank is running lean.The tip off here is you also said it "pings" when you start the truck cold.The "pinging" could be the exhaust leak.
     
  6. ABES

    ABES PlowSite.com Addict
    from MN
    Messages: 1,322

    B&B i was just thinking today that could be the problem.i have noticed the ticking from the drivers side of the motor under accelleration. my buddy had the same problem on his F-150 when his header gasket went bad. now i just need to decide if i should spend the cash on a new set of headers or a new manifold or just try a new gasket and see if that helps. thanks for the help guys
     
  7. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    It could be an intake leak too, getting too much air for the gas supplied by the EFI. My Windstar would throw the same code (statement). They replaced the intake gaskets under warranty and it never came back.
     
  8. ABES

    ABES PlowSite.com Addict
    from MN
    Messages: 1,322

    well this is wierd but ever since i cut out the mufflers and put in straight pipes the engine light went off and the truck has way way more power i think the mufflers were clogged because when i shoke them around there was a bunch of loose crap rattling around inside them. i think this was why my truck would rattle was just because of the mufflers.
     
  9. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    My Brother in-law's GMC plow truck rattles when you let off on the gas. He does not care, it would drive me nuts if it was mine.