VOLVO
CPM-B1D2386 - Overheat Sensor. Bus Signal / Message Failures. Signal invalid
System
Combustion Pre-heater Module (CPM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsV40 (2013–), V40 Cross Country (2013–)
Show models by year and engine (2)
What does this fault code mean?
The CPM has logged an excessive temperature gap between the overheat thermostat and the sensor. The heater is then deactivated and the code is set. The cause may be air or a leak in the cooling system, a damaged water pump, a damaged coolant temperature sensor or a damaged overheat protection thermostat.
Possible causes
- Air or leakage in the cooling system
- Damaged water pump
- Damaged coolant temperature sensor
- Damaged overheat protection thermostat
What you can do
- 1Check that the cooling system does not leak and that there is no air in it
- 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 a temporary fault
- 3Check that the temperatures at the thermostat and the sensor roughly agree once the engine is warm
- 4If the fault returns, have a workshop measure the thermostat resistance and replace it if needed
Symptoms you may notice1
- The parking heater does not work
What the fault can affect2
- The heater is deactivated when the code is set
- If the heater is activated again, it makes a new start attempt
General guidance for car owners. Diagnosis on the car can point to a different cause.