VOLVO
CEM-U000700 - High Speed CAN Communication Bus (-) Low. 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?
On the V40 the negative wire of the high speed CAN is shorted to earth, which disturbs communication between the control modules. The engine may have trouble starting, and performance and throttle response are affected. The fault most often lies in the high speed network wiring.
Possible causes
- Short circuit between the negative wire of the high speed CAN and earth
What you can do
- 1Note which driving faults occur and when. This shows whether the fault follows a certain stretch of the wiring
- 2Check the high speed harness for chafing and pinch damage where it moves
- 3Check the connectors on the network for loose connections, corrosion and moisture
- 4With a diagnostic tool, read the fault codes from all control modules and start with those for the CAN network
- 5Use a multimeter to check that the negative wire has no contact with earth or the body along its length
- 6If the engine stalls while driving, avoid long journeys and have a workshop trace the fault promptly
Symptoms you may notice4
- The engine does not start even though the starter turns
- Poor performance and lack of power
- The throttle response hesitates, surges or is jerky
- Cruise control cannot be engaged
General guidance for car owners. Diagnosis on the car can point to a different cause.