VOLVO
CEM-B108886 - LIN Bus "B". Bus Signal / Message Failures. Signal invalid
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 (IMS) and the siren (BBS) over a shared LIN bus. The fault shows that messages on the bus are corrupted, so the alarm may not work fully. The fault is checked when the alarm function is activated.
Possible causes
- Loose, corroded or high-resistance connections in the connectors
- Internal fault in the movement sensor (IMS)
- Internal fault in the siren (BBS)
What you can do
- 1Read off and note the code, clear it, then arm the alarm to see whether the code returns
- 2Check that the connectors to the movement sensor and the siren are fully engaged and not corroded
- 3Check that the fuse for the alarm is intact
- 4Use a multimeter (ignition off, connectors unplugged) to check that the LIN wire to the siren and movement sensor has no connection to ground or battery positive
- 5If you have a diagnostic tool, activate the alarm with the tool and check whether the siren responds
- 6If the fault remains, have a workshop check the movement sensor and the siren
Symptoms you may notice2
- The alarm does not start or gives no visible or audible signal
- 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.