VOLVO
CEM-DE1A - Communication with DEM control module. Signal missing
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 central module receives no communication from the four-wheel drive module (DEM), so four-wheel drive does not work. A text message and a warning symbol may also show in the display. The cause may be a missing supply or earth, contact resistance at connections, a break in the CAN wiring, or a module that is not intended for this car.
Possible causes
- No voltage supply to the four-wheel drive module (DEM)
- Open circuit in the earth lead to the four-wheel drive module (DEM)
- Contact resistance at the connections
- Open circuit in the CAN low-speed network wiring to the four-wheel drive module (DEM)
- The four-wheel drive module does not belong to this car, e.g. a used unit with other software
- Several fault codes for communication with other modules on the low-speed network point to a common fault on the CAN network
What you can do
- 1Check the connectors to the four-wheel drive module and look for corrosion or loose connectors
- 2With a multimeter, check that the supply wire to the module has no break and no contact with ground
- 3Also check the earth wire for a break and for a short to voltage
- 4Have a workshop check the CAN wiring and read the module ID, since faults on the CAN network need workshop equipment
Symptoms you may notice2
- Four-wheel drive does not work
- Text message and warning symbol in the display
General guidance for car owners. Diagnosis on the car can point to a different cause.