O2 sensors pre- and post-cat

[Terry]

Mark Romans wrote:
> 
> Hi Bruce:  At the GMTC they say the post cat o2 sensor is watching for
> change.  If you start getting changes in the 02 level then the cat isn't
> working.  Remember the OBD2 system is set up to watch for system
> degradation.  So the post cat 02 is there to monitor the effectiveness of
> the cat.  That's it.  I don't know if they set up any cute routines to check
> it.  But it was explained to me that it is watching for change.

And FWIW, if your application is for an "off road" type racing vehicle,
you can remove the cats & post-cat O2 sensors, then install some 
"O2 Simulators" available from Casper Electronics to keep the PCM 
happy & Trouble Code free.  They simulate the signal from the Post 
Cat O2 sensors...

Remember - for "off road" events only ;) 

T.