VOLVO
CEM-8FB1 - Rain sensor module (RSM). Internal fault
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 logged a fault inside the rain sensor module (RSM). The rain sensor then does not work, so the wipers cannot run automatically in the rain.
Possible causes
- Damaged rain sensor
- The rain sensor is not properly fixed to the glass
- Crack in the glass by the rain sensor
- Stone chip on the glass by the rain sensor
What you can do
- 1Clear the code and check whether it returns with the ignition on
- 2Check that the rain sensor is firmly fixed to the windscreen and has not come loose
- 3Look for cracks and stone chips in the glass by the rain sensor
- 4Check that the connector to the rain sensor is firmly seated and clean, with no oxidation or contact resistance
- 5If the fault returns or is permanent, have a workshop replace the rain sensor
Symptoms you may notice1
- The rain sensor function does not work
What the fault can affect1
- If the fault appears a while after the rain sensor is activated, the wipers switch to the highest speed
General guidance for car owners. Diagnosis on the car can point to a different cause.