VOLVO
CEM-4F31 - Battery temperature. 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 treats it as a fault when the signal wire from the battery temperature sensor is shorted to ground. The code is then set, and the battery may discharge. The battery temperature may also be shown incorrectly.
Possible causes
- The signal wire is shorted to ground
- A damaged battery temperature sensor
What you can do
- 1With a diagnostic tool, if you have one, check that the battery temperature in live data is reasonable
- 2Check that the connectors at the battery and at the CEM are seated and not corroded
- 3Use a multimeter to check that the signal wire from the battery sensor is not shorted to ground
- 4If the fault remains, have a workshop replace the battery temperature sensor
- 5After the work, clear the code and check that the battery charges normally
Symptoms you may notice1
- The battery discharges
What the fault can affect1
- The battery temperature is shown incorrectly
General guidance for car owners. Diagnosis on the car can point to a different cause.