VOLVO
CEM-U300801 - Control Module Ground "A". General Failure Information. General electrical failure
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsS80 (2007–), V70 (2008–), XC60 (2009–), XC70 (2008–)
Show models by year and engine (4)
What does this fault code mean?
The CEM has two earth connections, one for electronics and one for power. The fault is stored when the electronics earth has no connection to the car body, which can make some functions, such as the instrument panel, stop working.
Possible causes
- Contact resistance or oxidation in the terminals
- Open circuit in the earth cable
What you can do
- 1Check the earth connection at the module and at the body: it should be tight and free from rust and dirt
- 2Follow the earth cable from the module to the body and look for breaks, chafing and loose connectors
- 3Use a multimeter to check that the earth cable is connected to the body; if it is not, have a workshop repair the connection
- 4Reconnect connectors and components, switch the ignition on and check that the instrument panel works as it should
- 5Clear the code and road test; if it returns, have a workshop check the body earth connection
Symptoms you may notice3
- The combined instrument panel does not work
- The front seat power adjustment does not work
- The passenger compartment lighting does not work
What the fault can affect3
- The function turns off during the driving cycle in which the fault is detected
- If the fault stays present over many driving cycles the function is switched off permanently
- Erasing the trouble codes and starting a new driving cycle resets the function
General guidance for car owners. Diagnosis on the car can point to a different cause.