Cat over temperature protection question

[Moparmatty]

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?

[joecar]

No.

O2 sensors do not measure temperature.

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

[Moparmatty]

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

[joecar]

Turning off the rear O2S will prevent cat efficiency readiness test from running... but PCM will still calculate cat temperature.

[08z06]

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

[hog]

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

peace
Hog

[08z06]

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