Possible Causes
WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
| Possible Causes |
|---|
| (K99) O2 1/1 HEATER CONTROL CIRCUIT OPEN |
| (Z42) O2 1/1 HEATER GROUND CIRCUIT OPEN |
| (K99) O2 1/1 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE |
| O2 SENSOR |
| PCM |
Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.