Diagnostic trouble code (DTC) information CEM-5F3B

Condition 

Fig 1: Identifying Additional Heater And Parking Heater

Courtesy of VOLVO CARS OF NORTH AMERICA.

The central electronic module (HEM) checks the communication with the combustion preheater module (CPM).

The diagnostic trouble code (DTC) is stored if the central electronic module (HEM) registers that the signal in the circuit for the water pump is too low or missing.

The diagnostic trouble code (DTC) can be diagnosed when the heater is activated.

Substitute Value 

• None.

Possible Source 

• Contact resistance in the control module or water pump connectors
• Short-circuit to ground in the signal cable
• Open-circuit in the power cable
• Open-circuit in the signal cable
• Damaged water pump.

Fault symptom[s] 

• Poor heating in the passenger compartment
• The parking heater does not operate.