Possible Causes
| Possible Causes |
|---|
| (K99) O2 1/1 HEATER CONTROL CIRCUIT SHORTED TO GROUND |
| EXCESSIVE RESISTANCE IN THE (K99) O2 1/1 HEATER CONTROL CIRCUIT |
| 1/1 OXYGEN SENSOR |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to *PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .