Code P045, Rear Oxygen Sensor Signal Rich: Action

PCM turns on MIL. PCM turns on canister purge solenoid if Code P043 is also set.

1. If Code P013 is present, diagnose this code first since an oxygen sensor not ready can cause other emission related problems.
2. If oxygen sensor is operating correctly, voltage should fluctuate less than 0.6 volt. A rich sensor condition will cause voltage to remain at greater than 0.6 volt.
3. If voltage measured is less than 0.95 volt, PCM and circuit No. 1670 are okay.

Fig 1: Code P045 Schematic, Rear O2 Sensor Signal Rich

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P045 Diagnostic Flow Chart, Rear O2 Sensor Signal Rich

Courtesy of GENERAL MOTORS CORP.