VOLVO
CEM-1C04 - 30 Power supply. 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 voltage from the battery on the 30-supply is too high. The fault is intermittent, so it may have occurred before without being active now. The usual cause is a defective generator or battery. High voltage can burn out headlight bulbs and make the battery electrolyte boil.
Possible causes
- Defective generator
- Defective battery
What you can do
- 1Check that the battery terminals and cable connections are clean, tight and free of corrosion
- 2Check that the generator drive belt is correctly seated and not worn
- 3Check that the battery is not swollen or leaking. Replace it if it is damaged
- 4If you have a diagnostic tool, follow the battery voltage in live data with the engine running. The fault may be intermittent
- 5After the work, clear the code and check that the charging warning does not light again
Symptoms you may notice3
- The charging lamp lights while the engine is running
- The headlight bulbs burn out
- The battery electrolyte may boil with the engine running
General guidance for car owners. Diagnosis on the car can point to a different cause.