VOLVO
CEM-1A58 - Communication with the phone module (PHM). 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 phone module (PHM) and sets this code. The fault lies between the modules, so the CEM should not be replaced. The phone and its menu system may stop working, for example if the power supply to the phone module or its bus connection has been broken.
Possible causes
- The phone module is not getting power
- Contact resistance in the connections
- Open circuit on the CAN bus
- The phone module is defective
- The ground wire to the phone module is broken
- Wrong phone module for this car, for example a used module with different software or hardware
What you can do
- 1Check that the phone module is powered: press the on/off button and see whether the light in the button comes on
- 2Check that the connector to the phone module is seated and not corroded, chafed or damaged
- 3Check the phone module fuse. If it has blown, replace it once. If it blows again, use a multimeter to check the wire after it has no contact with ground.
- 4Check that the ground wire to the phone module is tight. Use a multimeter to check it has no break. If the fault remains, check the bus cable for breaks.
- 5After the work, clear the code and check that the phone works
Symptoms you may notice2
- The phone has reduced function or does not work
- The menu system does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.