VOLVO
CEM-5F3C - Heater fan. Signal too high
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–)
Show models by year and engine (10)
- Volvo S60 (2001–2009)2001, 2005–2009
- Volvo S60 (2001–2009)2002All engines except: D5244T2
- Volvo S60 (2001–2009)2003All engines except: B5244S6, D5244T2
- Volvo S60 (2001–2009)2004All engines except: B5244S6, B5254T4, D5244T2
- Volvo S80 (1999–2006)1999–2002, 2005–2006
- Volvo S80 (1999–2006)2003–2004All engines except: B5254T2
- Volvo V70 (2000–2008)2000–2003, 2005–2008
- Volvo V70 (2000–2008)2004All engines except: B5254T4
- Volvo V70 XC / XC70 (2001–2007)2001–2007
- Volvo XC90 (2003–)2003–2015
What does this fault code mean?
The central electronic module (CEM) monitors the heater fan in the parking heater. If the signal from the fan circuit is too high, for example because of a short to voltage, the code is set. The fault shows when the heater is active and appears as poor heating in the passenger compartment.
Possible causes
- Signal wire short-circuited to voltage supply
- Defective heater fan
- Damaged heater fan
What you can do
- 1Read and note the code, clear it and activate the heater fan to see whether the fault returns
- 2Listen for a buzzing sound which shows that the heater fan is running
- 3Check that the wiring and connectors to the fan are secure and free from corrosion
- 4Use a multimeter to check that the signal wire to the heater fan has no contact with voltage supply
- 5If the wire is intact and the fault remains, a workshop should replace the heater fan
Symptoms you may notice1
- Poor interior heating
General guidance for car owners. Diagnosis on the car can point to a different cause.