VOLVO
CEM-1A55 - Communication with the climate control module (CCM). 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 CEM has registered that communication with the CCM is not working, and the fault code is set. The climate control system may then stop working, and its lower row of buttons may not work. The fault code points to a communication fault in the CAN network, so the CEM should not be replaced.
Possible causes
- No power supply to the climate control module
- Break in the earth wire to the climate control module
- Contact resistance in the terminals
- Open circuit in the CAN wiring to the climate control module
- The climate control module is not meant for this car, for example a used module with other software or hardware
What you can do
- 1Switch on the climate control and check that the passenger compartment fan blows and that the fan speed can be changed
- 2Check the fuse for the climate control module's supply relay is intact
- 3Look for loose connectors and damage at the climate control module connector
- 4If you have a diagnostic tool, read the module ID; if it can be read, communication is probably fine and the fault may be intermittent
- 5Do not replace the CEM for CEM-1A5X codes; if the fault remains, have a workshop troubleshoot the CAN network
Symptoms you may notice3
- The climate control system does not work at all
- The bottom button row of the climate system does not work
- The climate control system works after the key has been removed
What the fault can affect1
- The climate control module keeps working for a short time after the key has been removed (limp-home)
General guidance for car owners. Diagnosis on the car can point to a different cause.