Engine light / – Air leak in exhaust before rear HO2S

Discussion in '80-Series Tech' started by LC96, Sep 6, 2011.

  1. LC96

    LC96

    Joined:
    Oct 29, 2007
    Messages:
    8
    Hi,

    I recently received a "Check Engine Light" - per Autozone the probable cause reads: 'Aaa1 - Air leak in exhaust before rear HO2S (heated oxygen sensors) Bank 1'

    Note: I had replaced my O2 sensors a couple years back.

    Has anyone ever received this message and would my local (trusted) auto repair guy be able to fix it?

    I am hoping this will not be a costly fix. :confused:

    Thanks in advance,

    LC96
    LC

    LC


    Aa1 – Air leak in exhaust before rear HO2S (heat oxygen sensor) Bank 1
    Aa1 – Air leak in exhaust before rear HO2S (heat oxygen sensor) Bank 1
    Aa1 – Air leak in exhaust before rear HO2S (heat oxygen sensor) Bank 1
     
  2. Ebag333

    Ebag333

    Joined:
    Oct 3, 2006
    Messages:
    8,163
    Location:
    Medford, OR
    What is the actual code? Should start with P0.
     
  3. LC96

    LC96

    Joined:
    Oct 29, 2007
    Messages:
    8
    Re: Code

    Hi - the code is "PO420" Thanks,
     
  4. Ebag333

    Ebag333

    Joined:
    Oct 3, 2006
    Messages:
    8,163
    Location:
    Medford, OR
    Searching will turn up lots of stuff. Basically the code means that the rear O2 sensor is reading too high. This could be due to an exhaust leak, or it could be due to your O2 sensor going bad.

    Searching the forums for P0420 will turn up a ton of results.
     
  5. LC96

    LC96

    Joined:
    Oct 29, 2007
    Messages:
    8
    Re:

    Thanks very much - I am now seeing all the related PO420 posts!......:)
     

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