VOLVO
CEM-U000500 - High Speed CAN Communication Bus (+) High. 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 positive wire of the high speed CAN is shorted to supply voltage, which disturbs communication between the control modules. The engine may then have trouble starting, and driving and the gauges are affected. The fault most often lies in the high speed network wiring.
Possible causes
- Short circuit between one of the CAN wires and supply voltage
What you can do
- 1Check whether the faults appear when the harness moves. That helps you find where the wire touches supply voltage
- 2Check the harness for chafing, pinch damage and moisture, especially at edges and grommets
- 3Check the high speed network connectors for loose connections and corrosion
- 4With a diagnostic tool, read the fault codes from all control modules. Communication faults in several modules point to a shared fault
- 5Use a multimeter to check that the positive wire has no contact with supply voltage when it should not
- 6If the engine stalls while driving, avoid long journeys and have a workshop trace the fault promptly
Symptoms you may notice5
- The engine does not start even though the starter turns
- Poor performance and lack of power
- The throttle response hesitates or surges under acceleration
- Cruise control cannot be engaged
- The speedometer and tachometer show wrong readings
General guidance for car owners. Diagnosis on the car can point to a different cause.