VOLVO
CEM-U100700 - Lost Communication With Battery Monitoring Sensor. General Failure Information. No sub type information
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 fault code means that CEM has lost contact with the battery monitoring sensor (BMS), which measures the battery state and sends the data to CEM. CEM uses this information to control charging. Without the contact, brake energy regeneration can be switched off.
Possible causes
- No voltage supply to the battery monitoring sensor (BMS)
- Broken ground wire to the BMS
- Contact resistance, oxidation or looseness in connectors and connections
- Damaged battery monitoring sensor (BMS)
- Open circuit in the communication wire to the BMS
What you can do
- 1Switch the ignition off and check the wire from the battery monitoring sensor to the battery positive terminal for breaks and shorts to ground
- 2Check the signal wire between the BMS and CEM for intermittent shorts or breaks, and for contact resistance and oxidation
- 3Switch the ignition on and read communication with a diagnostic tool. If it works but the code remains, the fault is probably intermittent
- 4If the fault returns, have a workshop check the wiring and replace the battery monitoring sensor if needed. Do not replace the CEM unless testing shows a fault in it
Symptoms you may notice1
- No noticeable symptoms for the driver
What the fault can affect1
- Brake energy regeneration function is switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.