VOLVO
CEM-1A64 - Communication with the differential electronic module (DEM). Signal missing
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
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 lost communication with the differential electronic module (DEM) and sets this code. The fault lies in the communication, not in the CEM, so the CEM should not be replaced. Four-wheel drive may stop working, and a warning may appear in the display or as a yellow warning lamp.
Possible causes
- The DEM is not getting power
- The ground wire to the DEM is broken
- Contact resistance in the connections
- Broken CAN wiring to the DEM
- Wrong DEM for this car, for example a used module with different software or hardware
- A common CAN network fault if several communication faults are stored at the same time
What you can do
- 1Check the DEM fuses in the cargo area and at the battery. If one has blown, replace it once. If it blows again, have a workshop check for a short.
- 2Check that the connectors to the DEM and the battery are seated, not corroded and free of play
- 3Check that the ground wire to the DEM is tight and clean. Use a multimeter to check it has no break
- 4If the fault remains, use a multimeter to check the wires to the DEM for breaks, and read the module ID with a diagnostic tool if you have one
- 5After the work, clear the code and check that the warning stays off. Have a workshop fix any remaining fault promptly, since four-wheel drive affects handling.
Symptoms you may notice4
- Four-wheel drive does not work
- A message appears in the display
- The anti-spin lamp is lit (model year 2002 and earlier)
- The general yellow warning lamp is lit (model year 2003 and later)
General guidance for car owners. Diagnosis on the car can point to a different cause.