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

[TheOtherNick]

I just installed my 02 Sim and it worked no more ses light. I will scan my car tomorrow to see if it is still running rich. I would assume it is not because i no longer have the code front 02 insufficient switching from running rich all the time.

[Sinister Performance]

I just installed my 02 Sim and it worked no more ses light. I will scan my car tomorrow to see if it is still running rich. I would assume it is not because i no longer have the code front 02 insufficient switching from running rich all the time.

The insufficent switching DTC is not caused by these diagnostic tests running. It will only set if the PCM does not see an O2 sensor hooked up and working. These diagnostic tests that the PCM runs causes the engine to run rich and lock fuel trims to max positive amounts UNTIL the PCM sees the expected return signal from the Post-Cat O2 sensor (signal = high voltage). BUT once a Post-Cat O2 sensor DTC sets, all of these diag. tests will cease running.

Dave @ TripleEdge reported earlier that an O2 sim DID NOT fix this issue for him. If it works for you, great. Just make sure you watch the scanner readings and make sure your fuel trims are not locking full rich while driving (and at the same time the pre-cat O2 sensor is outputting high voltage - above 0.750v). If this is happening, your PCM is running these diag. tests and you will need to take action to correct them.