VOLVO
CEM-8FA2 - Relay, horn. Activated too long
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
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 that the relay for the horn has been activated for too long. The horn then sounds constantly, and a wire that has come into contact with battery voltage may be the cause.
Possible causes
- Signal wire to the horn relay shorted to battery voltage
What you can do
- 1If the horn sounds constantly, pull the horn fuse to silence it until the fault has been traced
- 2Clear the code once the horn is silenced and check whether it returns
- 3If you have a diagnostic tool, read the horn switch in live data: its status should change when you press and release the horn
- 4If the status does not change the fault is permanent; if it changes the fault has occurred before and is intermittent
- 5With the ignition off, use a multimeter to check that the signal wire to the horn relay has no contact with battery voltage
Symptoms you may notice1
- The horn sounds constantly
General guidance for car owners. Diagnosis on the car can point to a different cause.