VOLVO
CEM-1A65 - Communication with the suspension module (SUM). Signal missing
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008)
Show models by year and engine (3)
What does this fault code mean?
The central electronic module (CEM) has lost communication with the suspension module (SUM) and sets this code. The fault lies in the communication, not in the CEM, so the CEM should not be replaced. The Four-C system, which controls chassis damping, does not work, and a general warning lamp may light.
Possible causes
- The SUM is not getting power
- Contact resistance in the connections
- Broken CAN bus
- The SUM is defective
- The ground wire to the SUM is broken
- Wrong SUM for this car, for example a used module with different software or hardware
What you can do
- 1Check the SUM fuses. If one has blown, replace it once. If it blows again, use a multimeter to check the wire after it has no contact with ground.
- 2Check that the connectors to the SUM and the wiring mat are seated and not corroded, chafed or damaged, and that the battery connection is clean
- 3Check that the relay for the SUM power supply is seated and clean. If the CEM has fault codes for this relay, trace those first
- 4If you have a diagnostic tool, read the SUM module ID. If it reads, the bus is probably intact and the fault may be intermittent
- 5After the work, clear the code and check that the Four-C function works
Symptoms you may notice2
- The general warning lamp is lit
- The Four-C function does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.