Alternative Fuel Control Module KAM Error
The engine computer's memory for the alternative fuel system (like CNG or propane) got corrupted, similar to a USB drive losing its saved settings. The vehicle can't properly store and recall fuel adjustment data needed to run the engine smoothly on alternative fuel.
The ECM monitors the Keep-Alive Memory (KAM) integrity of the alternative fuel control module, which stores learned fuel trim values and calibration data. If the KAM checksum fails or data corruption is detected, the fault triggers. The system validates memory addresses and data consistency during startup and operation.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| KAM Checksum | Checksum matches stored values | Checksum mismatch or data corruption detected |
| Memory Integrity | All memory locations readable and valid | Unreadable or invalid data in KAM locations |
Code P0618 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0618 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.