VOLVO
CEM-B104F16 - Switch Polling Pullup. General Electrical Failures. Circuit voltage below threshold
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsV40 (2013–), V40 Cross Country (2013–)
Show models by year and engine (2)
What does this fault code mean?
The CEM briefly powers several switches and contacts, such as those for the doors, bonnet, clutch pedal and brake lights, before reading them. The code is stored when these inputs have been powered during sleep mode, which raises the quiescent current draw. The code does not necessarily mean the CEM itself is faulty.
Possible causes
- Internal fault in the CEM
- Insufficient battery voltage, which can set the code without the CEM being faulty
What you can do
- 1Switch the ignition off and on once, then read off the codes again
- 2Check the battery charge and condition, and that the terminal clamps are tight and free from corrosion
- 3Check that the connectors for the doors, bonnet, clutch pedal and brake lights are fully engaged and not damaged
- 4If you have a diagnostic tool, follow in live data how the status of the doors, tailgate and brake lights changes when you open, close and press the brake
- 5If the code only appears occasionally, usually no action is needed; if it keeps coming back, have a workshop with diagnostic equipment check the central electronic module
Symptoms you may notice2
- The battery is weak
- The battery may be completely flat
General guidance for car owners. Diagnosis on the car can point to a different cause.