Chart A-7 Left Oxygen Sensor Not Ready

PFI Chart A-7:

PFI Oxygen Sensor Circuit:

DESCRIPTION:

The PCM/ECM provides a 0.45 volt reference signal to the oxygen sensor on CKT 912. When warm, a properly operating oxygen sensor will drive the 0.45 volt reference lower (below 0.45 volts) to indicate a lean mixture and higher (above 0.45 volts) to indicate a rich mixture.

NOTES ON FAULT TREE:

1. At key on with oxygen sensor disconnected, the parameter ED32 should read .45 volts (nominal). Lower or higher voltage indicates circuit problems.

2. The PCM/ECM compares voltage on CKT 912 to the ground voltage on CKT 413. It is essential that the oxygen sensor ground and PCM/ECM ground show good continuity (no voltage difference with engine running).