VOLVO
ECM-CD0C - Secondary battery charging. Voltage too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module checks the secondary battery voltage while the secondary battery relay is closed and the secondary battery is being charged. The voltage should then be close to the vehicle's other voltage. The fault is set when the voltage stays too low for a while. Applies only to cars with automatic start/stop.
Possible causes
- Contact resistance or oxidation in the connections
- Damaged secondary battery relay
What you can do
- 1Check that the fuses are intact. Their locations are in the owner's manual
- 2Check that the battery is charged and that the battery terminals are tight
- 3Check the connections at the secondary battery and the relay for contact resistance and oxidation
- 4If you have a diagnostic tool: read the secondary battery voltage in live data with the engine running and check that it is close to the vehicle's other voltage
- 5Erase the fault code and road test the car with automatic start/stop to see whether it returns
- 6If the fault remains, have a workshop check the secondary battery relay
Symptoms you may notice1
- No noticeable symptoms for the driver
General guidance for car owners. Diagnosis on the car can point to a different cause.