Possible Causes
| Possible Causes |
|---|
| (K399) O2 2/2 HEATER CONTROL CIRCUIT OPEN |
| (Z42) O2 2/2 HEATER GROUND CIRCUIT OPEN |
| 2/2 O2 SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure