March 25, 2026 Service bulletin

Flash: Ignition System Control Module (ISCM) Updates Customers must experience a Malfunction Indicator...

Jeep technical service bulletin 08-136-26 for 2023 Jeep Wagoneer and 2023 Jeep Grand Wagoneer.

Bulletin number: 08-136-26
Component: Engine
Summary: Flash: Ignition System Control Module (ISCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P2C30-00 - Ignition Coil Primary Circuit Fuse A. ● P2C31-00 - Ignition Coil Primary Circuit Fuse B. ● P0300-00 - Multiple Cylinder Misfire. ● P0301-00 - Cylinder 1 Misfire Detected. ● P0302-00 - Cylinder 2 Misfire Detected. ● P0303-00 - Cylinder 3 Misfire Detected. ● P0304-00 - Cylinder 4 Misfire Detected. ● P0305-00 - Cylinder 5 Misfire Detected. ● P0306-00 - Cylinder 6 Misfire Detected. ● P0420-00 - Catalyst System Efficiency Below Threshold Bank 1. ● P0430-00 - Catalyst System Efficiency Below Threshold Bank 2. Customers may also comment on the following: ● Engine hesitates/misfires. This bulletin involves inspecting and possibly reprogramming the ISCM with the latest available software.

Owners of these vehicles have filed 70 complaints in the engine category.

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