Pcm Code P044 - Rear Oxygen Sensor Lean Signal: Notes

PCM provides a .45-volt reference signal to oxygen sensor on circuit No. 412. 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 begin to generate a signal voltage. In a rich environment, signal voltage will be greater than .45 volt. In a lean environment, signal voltage will be less than .45 volt. If PCM is in good control of air/fuel mixture, mixture will change from rich to lean rapidly (at least one change every 2 seconds).

PCM Code P044 sets if oxygen sensor stays at lean voltage for more than 50 seconds during test conditions. PCM Code P044 also sets when oxygen sensor circuit fails or when air/fuel ratio is actually lean due to vacuum leak or fuel control system fault.