Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information CEM-DE18

Condition

Components Engine Coolant Heater (Part 1):

The diagnostic trouble code (DTC) is stored if the central electronic module (CEM) registers that communication with the combustion preheater module (CPM) is not operating.

Note! In the event of CEM-DEXX diagnostic trouble codes (DTCs) being stored the central electronic module (CEM) must not be replaced; the diagnostic trouble code (DTC) indicates a communication fault in the Control area network!

The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute value
- None.

Possible source
- No power supply to the combustion preheater module (CPM)
- Open-circuit in the ground lead to the combustion preheater module (CPM)
- Contact resistance in the terminals
- Open-circuit in the wiring for the CAN low speed network to the parking heater control module (CPM)
- The combustion preheater module (CPM) is not intended for this car (for example a used control module with different software/hardware).

Hint: If several diagnostic trouble codes (DTCs) are stored in the central electronic module (CEM) for communication faults with other control modules in the low speed network, this indicates a common fault in the Control area network, see the wiring diagram.

Fault symptom[s]
- The parking heater does not operate.