VOLVO
CEM-U025200 - Lost Communication With Lighting Control Module - Rear "B". General Failure Information. No sub type information
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
7 modelsS60 (2011–), S80 (2007–), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–)
What does this fault code mean?
The fault code means that the control module storing the fault has lost its link to a module on the network; although the code is named after the rear lighting module "B", it concerns the trailer module (TRM). Trailer lamps may then work wrongly. The fault concerns the network rather than one individual control module.
Possible causes
- No voltage supply to the trailer module (TRM)
- Broken ground wire to the TRM
- Poor contact in the connections
- Open or shorted CAN wiring
- A module not intended for the car, such as a used unit with other software or hardware
What you can do
- 1Check the supply voltage and body ground point to the TRM, and confirm the connectors are secure
- 2Check the ground wire to the TRM for breaks or a short to voltage
- 3Check the trailer hitch connector for contact resistance and oxidation
- 4If the fault returns, have a workshop check the CAN wiring. Replace the CEM only if testing shows it is damaged
Symptoms you may notice1
- Trailer lamps do not work correctly
General guidance for car owners. Diagnosis on the car can point to a different cause.