Possible Causes
| Possible Causes |
|---|
| (K399) O2 2/2 HEATER CONTROL CIRCUIT SHORTED TO VOLTAGE |
| (K399) O2 2/2 HEATER CONTROL CIRCUIT OPEN OR HIGH RESISTANCE |
| (Z904/Z920) GROUND CIRCUIT OPEN OR HIGH RESISTANCE |
| 2/2 OXYGEN SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .