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Thread: Cat over temperature protection question

  1. #1
    Junior Member
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    Default Cat over temperature protection question

    This question is in regards to a 2005 GMC Sierra 5.3L auto.

    Is it the downstream O2 sensors that monitor the temp for the CAT over temperature protection function?

  2. #2
    Joe (Moderator) joecar's Avatar
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    No.

    O2 sensors do not measure temperature.

    The PCM calculates the catalyst temperature based on fueling, timing, torque, load aand a few other things.

  3. #3
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    Thanks Joe. I just wanted to be sure that with turning off the rear O2's I didn't cause any issues.

  4. #4
    Joe (Moderator) joecar's Avatar
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    Turning off the rear O2S will prevent cat efficiency readiness test from running... but PCM will still calculate cat temperature.

  5. #5
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    If you are disabling the rear O2's does it make sense to disable cat protection in the ECU?

  6. #6
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    N ot necessarily, if you are removing teh cats, it would make sense to disable the cat protection protocol.

    peace
    Hog
    1997 rcsb stock L31 longblock, Marine Intake with 28# EV6 injectors, L35 2700 stall TC,Hooker LT's 2.007 60ft

  7. #7
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    My cats are gone, so I will disable the cat protection maps.

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