VOLVO
CPM-B1D3466 - Heater in lock out mode. Algorithm Based Failures. Signal has too many transitions / events
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 heater has overheated more than ten times in a row, and the control module has therefore locked it in the switched-off state. The fault code may be set together with other fault codes, and the cause may lie in the cooling system, for example in a sensor, a thermostat or the pump.
Possible causes
- Damaged coolant temperature sensor
- Damaged overheat protection thermostat
- Air or leakage in the cooling system
- Damaged water pump
What you can do
- 1With the ignition on, read the fault codes. Fix any other stored fault codes first, as they may be the cause.
- 2Check that the cooling system does not leak and that the hoses to the heater are firmly attached. A leak gives a low coolant level.
- 3If you have a diagnostic tool: watch the coolant temperature in live data while the heater runs, and see whether it rises and falls evenly.
- 4If the fault returns after these checks, have a workshop check the water pump and the overheat protection thermostat.
Symptoms you may notice1
- The parking heater does not work
What the fault can affect1
- The heater locks in the switched-off state after repeated overheating
General guidance for car owners. Diagnosis on the car can point to a different cause.