VOLVO
CEM-8A20 - Low beam left. Signal too low
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:
5 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
What does this fault code mean?
The central electronic module (CEM) supplies the left-hand low beam directly from one output. The module has registered a current draw on that output that is too high, which points to the signal wire to the lamp being shorted to ground. If the fault keeps returning over several ignition cycles, the output is switched off completely until the code is cleared.
Possible causes
- The signal wire to the left low beam lamp is short-circuited to ground
What you can do
- 1Check that the low beam fuse is intact and that the left bulb sits firmly in its holder
- 2With the ignition off and the connector to the left low beam unplugged, use a multimeter to check that the wire has no contact with ground (the body)
- 3Look for chafed or pinched spots along the wire, especially where it enters the headlamp and the wiring harness. A chafed spot can make contact with the body
- 4Clear the code and switch on the low beam to see whether the fault returns
- 5If the fault returns, have a workshop with diagnostic equipment check the wiring and the module
Symptoms you may notice1
- The left low beam does not work
What the fault can affect1
- The output to the left low beam is switched off permanently after repeated faults, until the code is cleared
General guidance for car owners. Diagnosis on the car can point to a different cause.