VOLVO
CEM-DE42 - Communication with CRM control module. Signal missing
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
1 modelC70 (2006–2013)
Show models by year and engine (1)
What does this fault code mean?
The CEM has no contact with the convertible roof module (CRM), so the roof cannot be operated fully or partly and the lockable storage compartments may stop working. Common causes are supply, earth or a connector at the CRM, or a break in the LS-CAN wiring.
Possible causes
- No supply to the CRM
- Open circuit in the earth wire to the CRM
- Contact resistance in the connections
- Open circuit in the LS-CAN wires to the CRM
- The CRM does not suit the vehicle, for example if a control module with different software or hardware has been fitted
What you can do
- 1Check that the main fuse at the battery and the roof fuse are intact
- 2Use a multimeter to check that the supply wire to the CRM has no break and is not shorted to earth
- 3Check the CRM earth point for loose contact or corrosion, and that the wire between the earth point and the module is intact
- 4With a diagnostic tool, read the CRM ID. If it reads, the communication is probably fine and the fault may be intermittent and harder to find
- 5Do not replace the CEM for this code; it shows a communication fault on the CAN network
Symptoms you may notice2
- No roof operation or only limited roof operation
- Lockable storage compartments fully or partly do not work
General guidance for car owners. Diagnosis on the car can point to a different cause.