VOLVO
CEM-2E01 - Relay, horn 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 found the horn relay shorted to ground. The horn does not work in this case. The fault is most often caused by a broken relay.
Possible causes
- A damaged relay
What you can do
- 1Check the horn fuse in the engine bay fusebox. If it has blown, replace it once
- 2Replace the horn relay with an identical one. If the horn then works, the old relay was probably faulty
- 3Check that the connectors at the relay and at the CEM are seated and not corroded
- 4With the relay removed, use a multimeter to check that the horn wire is not short-circuited to ground
- 5After the work, test the horn and check that the code does not return
Symptoms you may notice1
- The horn does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.