Diagnostic trouble code information

Condition 

Fig 1: Additional Heater And Parking Heater (Combustion Preheater Module)

Courtesy of VOLVO CARS OF NORTH AMERICA.

If the control unit indicates that a start attempt has failed, diagnostic trouble code CEM-5F4F will be stored.

Substitute Value 

• The heater is not activated.

Possible Source 

• No fuel feed.
• Flame indicator covered with soot.
• Blocked combustion air flow.
• Contact resistance in control unit connector.
• Open circuit or short circuit to voltage supply on the control signal wire of the flame indicator.
• Damaged flame sensor.

Fault symptom[s] 

• Poor interior heating.