VOLVO
CEM-U300813 - Control Module Ground "A". General Electrical Failures. Circuit open
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?
On the V40, the central electronic module (CEM) monitors whether it has access to electronic earth. The fault is stored when the module has no electronic earth, for example after a break in the earth cable. When there is a break, affected relays in the car clatter.
Possible causes
- Open circuit in the cable for electronic earth
What you can do
- 1Check the electronic earth cable at the module and at the body: it should be tight and free from rust
- 2Follow the cable and look for breaks, chafing and pinch damage, especially where it moves
- 3Use a multimeter to check the cable has contact with the body; if not, replace the cable or have a workshop repair it
- 4Listen when the ignition is switched on: if relays clatter, that is a clear sign the earth connection is failing
- 5If the fault returns after repair, have a workshop with diagnostic equipment check the module
Symptoms you may notice5
- The car performs poorly and lacks power, especially when pulling away
- The engine does not start, or cranks without starting
- The car hesitates, surges or feels jerky when driving
- Cruise control cannot be engaged
- Gauges show wrong readings or do not work
General guidance for car owners. Diagnosis on the car can point to a different cause.