VOLVO
CPM-1604 - Water pump. Signal missing
System
Combustion Pre-heater Module (CPM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CPM has registered a break in the cable to the water pump, so the signal is missing. The cause may be a broken cable, poor connections, or a pump that is blocked or damaged. The heater cannot be activated until the code has been cleared.
Possible causes
- Open circuit in the cable between the CPM and the water pump
- Contact resistance, oxidation or loose connections
- Blocked water pump
- Damaged water pump
What you can do
- 1Clear the code and try starting the heater again
- 2If you have a diagnostic tool, activate the water pump; if it does not start, the fault is probably permanent, while a pump that starts points to an intermittent fault
- 3Check the connectors at the heater and at the water pump: they should be secure and free from oxidation
- 4Use a multimeter to confirm voltage at the water pump connector when the heater starts; if it is missing, the cable is a likely cause
- 5If there is no fault in the cables or connectors the pump may be blocked: have a workshop check it and replace the water pump if needed
Symptoms you may notice2
- Poor heating in the passenger compartment
- The parking heater does not work
What the fault can affect1
- The heater cannot be activated until the fault code has been cleared
General guidance for car owners. Diagnosis on the car can point to a different cause.