Possible Causes
| Possible Causes |
|---|
| (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE |
| (K904) O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO VOLTAGE |
| (K243) O2 2/2 SIGNAL CIRCUIT OPEN |
| (K904) O2 RETURN DOWNSTREAM CIRCUIT OPEN |
| 2/2 O2 SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .