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

[specialeditiongtp]

I have an 01 gtp with a 3" catless down pipe and a zzp 1.0 pcm, and i think i might have this problem. It does seem to run a little fat, it has been this way for a bout a year. Is this something to worry about, what is the worst thing that could happen?

[Sinister Performance]

I have an 01 gtp with a 3" catless down pipe and a zzp 1.0 pcm, and i think i might have this problem. It does seem to run a little fat, it has been this way for a bout a year. Is this something to worry about, what is the worst thing that could happen?

The worst thing that could happen is the engine running too rich a lot of the time which COULD result in what's known as "cylinder wash-down" of gasoline. Basically the cylinders will glaze up causing excessive blow-by and you will end up with a lot of gasoline making it into your oil which COULD result in eventual engine bearing failure.

Of course this is the worse-case-scenario and it may never happen to your car. Depends on a lot of factors. Best thing you can do is hook up a scan tool or other scanning device and watch your fuel trims and front O2 sensor voltage readings. If your PCM is locking the fuel trims high in the +'s and this results in the O2 voltage locking high (above 0.750 volts or so) for extended periods (more than 20 seconds) while driving, then you probably have the problem described in this thread and need to take action to prevent potential issues down the road.