What does fault code CEM-4F90 mean?

Diagnostic fault code details for CEM-4F90 (Volvo S60 (2001–2009), Volvo S80 (1999–2006), Volvo V70 (2000–2008)). Repair service at OBD Tuning.

VOLVO

CEM-4F90 - Seat belt reminder. Signal too high

System

Central Electronic Module (CEM)

Volvo models this fault code applies to

Applies to the following models:

5 models

S60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)

Show models by year and engine (5)

What does this fault code mean?

The CEM checks the signal from the seat belt reminder sensor in the passenger seat. If the sensor level is too high, the code is set. A general warning lamp may then light.

Possible causes

Short to supply voltage in the signal cable
A damaged seat belt reminder sensor

What you can do

1Safety: the seat belt reminder sensor is part of the crash protection. Do not work on it or its wiring yourself. Have a workshop check it
2Look at the connectors to the sensor under the passenger seat without removing anything. A workshop should fix any that are loose or damaged
3After the work, clear the code and check that the warning lamp goes out

Symptoms you may notice1

General warning lamp lit

General guidance for car owners. Diagnosis on the car can point to a different cause.