Diagnostic trouble code information

Condition 

Fig 1: Identifying Flame Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

If the flame goes out unexpectedly during operation, this will be interpreted by the control unit as a fault and diagnostic trouble code CEM-5F39 will be set.

Substitute Value 

• None.

Possible Source 

• No fuel feed.
• Flame indicator covered with soot.
• Damaged flame sensor.
• Contact resistance in control unit connector.
• Open circuit in signal wire.
• Signal wire short-circuited to voltage supply.
• Open circuit in ground wire.

Fault symptom[s] 

• Poor interior heating.