Possible Causes
| Possible Causes |
|---|
| (K399) O2 2/2 HEATER CONTROL CIRCUIT OPEN |
| (Z992) O2 2/2 HEATER GROUND CIRCUIT OPEN |
| (K399) O2 2/2 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE |
| O2 SENSOR |
| PCM |
Always perform PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.