Possible Causes
| Possible Causes |
|---|
| O2 1/2 RETURN CIRCUIT OPEN/HIGH RESISTANCE |
| O2 1/2 SIGNAL CIRCUIT OPEN/HIGH RESISTANCE |
| O2 1/2 SIGNAL CIRCUIT SHORTED TO THE O2 1/2 RETURN CIRCUIT |
| O2 SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to STANDARD PROCEDURE .