VOLVO
CEM-B108888 - LIN Bus "B". Bus Signal / Message Failures. Bus off
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 CEM talks to the movement sensor and the siren over a shared LIN bus. The fault shows that the messages the CEM sends never reach the bus, so the alarm parts cannot be controlled.
Possible causes
- The LIN bus is shorted to voltage or to ground
- Internal fault in the movement sensor (IMS)
- Internal fault in the siren (BBS)
What you can do
- 1Clear the code and check whether it returns after locking the car with the remote control
- 2Check that the connectors to the movement sensor and the siren are fully engaged and dry
- 3Check that the fuse for the alarm is intact
- 4Use a multimeter (ignition off, connectors unplugged) to check that the LIN wire has no connection to ground or battery positive
- 5If you have a diagnostic tool, read the alarm status in live data and check whether it changes when you lock and unlock the car
- 6If the fault remains, have a workshop check the movement sensor and the siren
Symptoms you may notice2
- The alarm does not start
- Other alarm functions do not work correctly
What the fault can affect1
- The siren beeps several times if the bus communication drops out
General guidance for car owners. Diagnosis on the car can point to a different cause.