VOLVO
CEM-B1C8412 - Heated rear window relay output circuit. General Electrical Failures. Circuit short to battery
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 central electronic module (CEM) controls the heated rear window. The code is set when the output signal is too high, which is caused by the supply wire to the rear window heater being shorted to voltage.
Possible causes
- The supply wire to the rear window heater is shorted to voltage
What you can do
- 1Read and clear the code, then switch on the rear window defroster and see whether it heats
- 2Check the rear window heater fuse in the passenger compartment fuse box
- 3Look for chafing and damaged insulation on the supply wire to the rear window heater
- 4Use a multimeter to see whether the supply wire has voltage with the ignition off, which shows a short to voltage
- 5If the wire is intact, have a workshop with diagnostic equipment check the module output
Symptoms you may notice1
- Electric heating of the rear window does not work
What the fault can affect3
- The function switches off during the driving cycle in which the fault is detected
- After repeated driving cycles with the fault, the function is switched off permanently
- Clearing the fault codes and starting a new driving cycle resets the output
General guidance for car owners. Diagnosis on the car can point to a different cause.