Possible Causes
| Possible Causes |
|---|
| (K299) O2 1/2 HEATER CONTROL CIRCUIT OPEN |
| (Z42) O2 HEATER GROUND CIRCUIT OPEN |
| 1/2 O2 SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .