VOLVO
CEM-B1A7915 - Rear Fog Lamp. General Electrical Failures. Circuit short to battery or open
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
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 CEM supplies the rear fog lamps directly through an output and checks the signal. The fault is stored when the signal from the output is too high, which may be caused by poor contact, a break in the signal wire, or a supply wire short-circuited to voltage. The fault is checked with the fog lamps switched off.
Possible causes
- Contact resistance, oxidation or poor contact in the connections
- Open circuit in the signal wire
- The supply wire is short-circuited to voltage
What you can do
- 1Check that the fuses are intact
- 2Check that the fog lamps are switched off and see whether the rear lamps still light, then clear the fault code and road test
- 3Check the connectors at the lamps and at the CEM, and the wiring, for breaks and chafing
- 4Use a multimeter to check that the supply wire is not short-circuited to battery voltage when the connectors are disconnected
- 5If the fault returns, have a workshop with diagnostic equipment fault-trace the control module and the wiring
Symptoms you may notice2
- The rear fog lamps do not work
- A text message and a warning symbol appear in the display
What the fault can affect2
- The function switches off permanently after 100 driving cycles where the fault was detected
- Erasing the fault codes resets the output
General guidance for car owners. Diagnosis on the car can point to a different cause.