VOLVO
CPM-B12B211 - AUX Heater Coolant Diverter Valve. General Electrical Failures. Circuit short to ground
System
Combustion Pre-heater Module (CPM)
Volvo models this fault code applies to
Applies to the following models:
1 modelV60 (2011–)
Show models by year and engine (2)
What does this fault code mean?
The combustion preheater module (CPM) measures the resistance across the coolant diverter valve for the auxiliary heater. The code is set when the valve has an electrical fault, here a short to earth. The heater's function is then blocked.
Possible causes
- Damaged cable to the distribution valve
- Damaged connector
- Distribution valve shorted to earth
- Damaged distribution valve
What you can do
- 1Check the cable to the diverter valve visually for any damage
- 2Check that the connector at the diverter valve is secure and free from oxidation
- 3Use a multimeter to check that the cable has no contact with the body (earth); if it does, the cable is shorted
- 4Clear the code and start the heater again to see whether the fault returns
- 5If the fault is not fixed, have a workshop replace the diverter valve
Symptoms you may notice5
- The parking heater does not work
- The rear of the cabin is not warm enough
- The front of the cabin is not warm enough
- The heater does not work
- The cabin heats up slowly
What the fault can affect1
- The heater's function is blocked
General guidance for car owners. Diagnosis on the car can point to a different cause.