Possible Causes
| Possible Causes |
|---|
| (K99) O2 1/1 HEATER CONTROL CIRCUIT OPEN |
| (Z904) O2 1/1 HEATER GROUND CIRCUIT OPEN |
| (K99) O2 1/1 HEATER CONTROL SHORTED TO BATTERY VOLTAGE |
| O2 SENSOR |
| PCM |
Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.