Code P045, Rear Oxygen Sensor Rich Signal: Notes

PCM provides a .45-volt reference signal to oxygen sensor on circuit No. 1670. When oxygen sensor temperature is less than 392°F (200°C), sensor signal voltage will be about .45 volt and PCM will keep system in open loop operation. When oxygen sensor temperature is greater than 392°F (200°C), sensor will swing from rich to lean rapidly, at least one swing every 2 seconds, if PCM is in good control of air/fuel mixture.

Code P045 sets when sensor stays at a rich voltage for more than 50 seconds during the test conditions. Code P045 will also set when oxygen sensor circuit fails or when air/fuel ratio is actually rich due to fuel control or emissions system fault.