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check engine light????

Discussion in 'Chevy Tahoe Forum (GMC Yukon, Cadillac Escalade)' started by twiggy, May 7, 2009.

  1. twiggy

    twiggy Member

    So every once-in-awhile i get a check engine light, i put my OBD2 scanner on it and it give's me the same code every time- "catalyst effieciantcy below threshold" , I'm not sure what that means.
    Any ideas????

    Attached Files:

  2. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    check engine light???

    Looks like your cat took a dump.:frown:
  3. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    Yep, bad cat or bad O2 sensor. You don't state the code number or which bank, when I got that code (P0430), I switched the post cat O2 sensors to see if the code followed the sensor or not. Once I determined it wasn't the sensor, I replaced the cat.
  4. twiggy

    twiggy Member

    Honestly, i dont even have a cat, it didnt have them when i bought the truck. could the previous owners wired something wrong when installing the dual exhaust?
  5. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    If there is no cat, that is why the computer is telling you the cat is inefficient. You will have to put cats in to make it go away.
  6. twiggy

    twiggy Member

    well i can erase the codes with my scanner. and after i erase it, the code comes back in about a month. so i'll just keep erasing the code

  7. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    When you clear the code it take a few cycles before it throws the code again. The truck doesnt know if the cat is removed or bad, it just sees dirty O2.

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