VOLVO
CEM-8FA3 - Relay, signal horn. No signal. Intermittent fault
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 fault is intermittent: the signal to the horn relay coil was missing or too low on an earlier occasion, but it is no longer present. The horn may then stop working, and the cause may be oxidation in the relay socket, a relay that is loose or missing, or a faulty relay.
Possible causes
- Oxidation in the relay socket contacts
- The relay is loose or missing
- Faulty relay, such as an open or short circuit to ground in the coil
What you can do
- 1Clear the code and check whether it returns; an intermittent fault can be a temporary disturbance
- 2Check that the horn relay sits firmly in its socket and is not loose
- 3Check that the contacts in the relay socket are clean and free of oxidation
- 4Test the horn with the ignition on; if it only works now and then, the fault has been intermittent
- 5If the fault returns, have a workshop check the relay's driver circuit and replace the relay if needed
Symptoms you may notice1
- The horn does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.