VOLVO
CPM-U001088 - Medium Speed CAN Communication Bus. Bus Signal / Message Failures. Bus off
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 control module has lost contact with the CAN network, because the communication has been blocked by a serious disturbance. The control module then disconnects itself (bus-off) and stays shut down. The fault may be caused by a short or open circuit in the CAN wiring, an internal fault in the heater control module, or a fault in another control module on the same part of the network.
Possible causes
- Short circuit between the CAN wires
- Open circuit in one of the CAN wires
- Internal fault in the heater control module
- Fault in another control module on the same part of the CAN network
What you can do
- 1With the ignition off, look at the connectors and CAN wiring to the heater for chafing, damage and corrosion.
- 2If you have a diagnostic tool, you can see whether other control modules show communication faults. If so, the fault is probably in the network.
- 3Check that the battery has good voltage, as low voltage can disturb communication.
- 4Have a workshop measure the resistance in the CAN network and check the traffic on the wiring with diagnostic equipment.
- 5Do not replace the heater control module until a workshop has established whether the fault lies in another module on the network.
Symptoms you may notice2
- The parking heater does not work
- Poor heating in the cabin
What the fault can affect3
- The control module disconnects itself from the network and stays shut down until its power is cut
- The heater's function is blocked
- The control module makes new communication attempts when it receives power again
General guidance for car owners. Diagnosis on the car can point to a different cause.