VOLVO
CEM-2E03 - Comfort Relay, Signal too low
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CEM has registered too low a signal from the output to the coil of the comfort relay. The fault may be caused by a damaged relay, a short to ground in the relay drive circuit, or an open circuit in the relay coil. The blower fan, the climate control and battery voltage may be affected.
Possible causes
- A damaged relay
- A short to ground in the relay drive circuit
- An open circuit in the relay coil
What you can do
- 1Check the fuses for the comfort functions in the passenger compartment and engine bay. If one has blown, replace it once
- 2The comfort relay is inside the CEM box. Replace it only if you can do so safely, otherwise have a workshop do it
- 3Check that the connectors in the CEM and at the fan are seated and not corroded
- 4Use a multimeter to check that the wire to the comfort relay has no short to ground
- 5After the work, clear the code and check that the fan works
Symptoms you may notice3
- The blower fan does not work
- The climate control smells unusual
- The battery may show low voltage
General guidance for car owners. Diagnosis on the car can point to a different cause.