VOLVO
CEM-8A12 - Low beam left. Faulty signal
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CEM feeds the left low beam directly from its own output. The module has registered that the current drawn by that output is too low, meaning the lamp is not drawing the current it should. The fault concerns the lamp or the wiring to it, so the check starts with the lamp and then moves on to the wiring.
Possible causes
- The left low beam bulb is faulty or missing
- Open circuit in the signal wire to the left low beam lamp
- The signal wire is short-circuited to supply voltage
What you can do
- 1Switch on the low beam. If the left lamp stays dark, the fault is likely permanent; if it lights but the code was stored earlier, it is intermittent
- 2Check the low beam fuse and that the left bulb sits firmly; replace the bulb with one of the correct type if it is faulty
- 3With the ignition off and the lamp connector unplugged, use a multimeter to check that the wire to the left low beam is not broken
- 4Look for chafing and pinched spots, especially at the headlamp. With the low beam off, check the wire has no supply voltage with a multimeter
- 5Clear the code after the repair and switch on the low beam to see whether the fault comes back
- 6If the fault returns, have a workshop with diagnostic equipment check the module and the wiring
Symptoms you may notice2
- The left low beam does not work
- The low beam may stay lit all the time
General guidance for car owners. Diagnosis on the car can point to a different cause.