VOLVO
CEM-1C21 - Relay, infotainment. Signal too high
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
1 modelXC90 (2003–)
Show models by year and engine (1)
What does this fault code mean?
The CEM registers that the signal to the coil of the infotainment relay is too high. The usual cause is a short to supply voltage in the relay circuit or a defective relay. The audio system does not work.
Possible causes
- A short to supply voltage in the relay circuit
- A defective relay
What you can do
- 1Check that the fuses for the infotainment relay are intact. If one has blown, replace it once
- 2Replace the infotainment relay with an identical one. If the audio system then works, the old relay was probably defective
- 3With the ignition on, check that the relay clicks when activated. A click shows that the relay works
- 4Use a multimeter to check the wire between the relay and the infotainment module for a short to supply voltage. If the fault remains, check the module with a diagnostic tool
- 5After the work, clear the code and check that the audio system works
Symptoms you may notice1
- The audio system does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.