VOLVO
CEM-9F24 - Rheostat. Signal too high. 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 central electronic module (CEM) has registered that the signal from the rheostat was too high at one point. The fault is intermittent, meaning it is sporadic, and may not be present now. The instrument lighting may stop working while the fault is active.
Possible causes
- Rheostat shorted to supply voltage
- Faulty light switch
What you can do
- 1Turn the dimmer control and check whether the instrument lighting suddenly changes brightness or goes out
- 2Check the connectors and wiring to the light switch for loose connections, chafing and corrosion; gently move the wiring while the instrument lighting is on
- 3Use a multimeter while the dimmer control is turned: if voltage in the rheostat wire appears or changes as it moves, the fault is there
- 4Clear the fault code and road test to see whether it returns
- 5If the fault returns, have a workshop with diagnostic equipment check the light switch, because intermittent faults are often not seen in a simple check
Symptoms you may notice1
- Instrument lighting does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.