What "faults" would make the PCM pin the voltage?

 

What you quoted is an incorrect statement. The PCM doesn't 'pin' O2 sensor voltages with faults. There is a bias voltage the PCM applies on the PCM sensor input pin of 450mv that the sensor drives higher and lower when working. That is why when you unplug a sensor a scanner will show 450mv and not 0mv.

 

I know this is an old thread but did you ever figure out what the issue was? I am having the same exact issue. Thanks!