VOLVO
CEM-9F25 - Rheostat. Signal too low. Intermittent fault
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 rheostat, which controls the brightness of the instrument lighting, has at one point sent too low a signal to the central electronic module (CEM). The fault is sporadic and may no longer be visible. The instrument lighting can then stop working.
Possible causes
- Rheostat shorted to earth
- Faulty light switch
What you can do
- 1Turn the dimmer control slowly and see whether the instrument lighting changes brightness in jumps or goes out
- 2Gently move the wiring and the light switch connector with the ignition on and see whether the instrument lighting is affected
- 3With the ignition off, use a multimeter to check whether the rheostat wire makes contact with earth when it is moved
- 4Clear the fault code and road test to see whether it returns
- 5If the fault returns, have a workshop check the rheostat and replace the light switch if needed
Symptoms you may notice1
- Instrument lighting does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.