VOLVO
CEM-4F40 - Seat belt buckle, right rear seat. Signal too low
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 monitors the right rear belt buckle. If the voltage is too low or the signal wire has a break, the code is set. The information lamp may light, and a message may appear in the display.
Possible causes
- Short to ground in the signal wire between the rear right seat belt buckle and the CEM
- Short to ground in the connector
- An open circuit in the signal wire inside the belt buckle
- An open circuit in the signal wire between the belt buckle and the CEM
- Cross-connected signal wires between the belt buckle and the CEM
- A damaged fuse
What you can do
- 1Check the fuse for the seat belt function in the passenger compartment. If it has blown, replace it once
- 2Safety: the seat belt system is part of the crash protection. Do not work on the wiring or the buckle yourself. Have a workshop check the wiring
- 3Look for chafed or pinched cables at the rear right seat belt, without removing anything
- 4After the work, clear the code and check that the information lamp goes out
Symptoms you may notice2
- The information lamp is lit
- A message appears in the display
General guidance for car owners. Diagnosis on the car can point to a different cause.