VOLVO
CEM-U004100 - Extended CAN Communication Bus (+) High. General Failure Information. No sub type information
System
Central Electronic Module (CEM)
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 fault code means that the positive (high) wire in the extended CAN network has contact with voltage. The network links the park assist camera, blind spot system and cross traffic alert with the rest of the car. Voltage on the wire disturbs communication, and the systems can stop working until the contact is gone.
Possible causes
- Wiring that has chafed or been pinched lets the positive extended-network wire touch voltage
What you can do
- 1Read and note the fault codes in the control modules, clear them and road test the car
- 2Switch the ignition off and check the wiring for chafing, pinch damage and connectors that are loose or corroded
- 3Use a multimeter to confirm the positive wire has no contact with voltage, and wiggle wiring and connectors during the test
- 4If the code returns, have a workshop with diagnostic equipment measure the voltage drop between modules. Replace the CEM only if testing shows it is faulty
Symptoms you may notice3
- Park assist camera does not work
- Blind spot monitoring (BLIS) does not function
- Cross Traffic Alert (CTA) does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.