Removing rear O2 sensor on 01-newer PCMs -- Things you should know

[apierce1289]

So if i want to run a race pipe that came with my speed daddy headers i just need to have an o2 sensor plugged into it even though there is no CAT. As long as the engine can read the o2 it wont keep running the diagnostic? Then just set the DTC's to no reporting? And everything should run a ok?

[Sinister Performance]

So if i want to run a race pipe that came with my speed daddy headers i just need to have an o2 sensor plugged into it even though there is no CAT. As long as the engine can read the o2 it wont keep running the diagnostic? Then just set the DTC's to no reporting? And everything should run a ok?

That's a good question. I don't know what would happen if you got rid of the cat and left the rear O2 in there. The Monte I tuned on didn't have a rear O2 or a cat so I never got to try it.

I would say go ahead and try disabling the catalyst codes only (leave the post-O2 codes enabled) and then watch your fuel trims as you drive and see if it tries to run the cat diagnostic. It may try to run it but should soon quit running it as the rear O2 would show rich immediately as the test begins.

Give it a try and let us know what happens.

-ryan