VOLVO
CEM-U000100 - High Speed CAN Communication Bus. General Failure Information. No sub type information
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 detected that communication on the high speed CAN is disturbed. The disturbance comes either from another module on the network or from the module's own messages disturbing the network. The module then switches itself off, and several functions can drop out. The code does not say more precisely what type of fault it is.
Possible causes
- Short circuit or open circuit on a CAN wire
- Internal fault in the module
- Internal fault in another module on the same part of the CAN network
What you can do
- 1Read the fault codes from all control modules. Start with the codes that concern the CAN network, since they are often the cause
- 2Check the high speed network connectors for loose connections, corrosion and moisture
- 3Gently flex the harness with the ignition on and see whether the communication fault changes
- 4With a diagnostic tool, clear the fault codes and run a short test. If the fault returns straight away, it is active
- 5Resistance measurements in the CAN network are best made by a workshop, since the network must be separated
- 6Have a workshop establish whether one module is disturbing the network. That module then normally needs replacing
Symptoms you may notice5
- The starter turns but the engine does not start
- The speedometer does not work
- The tachometer does not work
- The coolant temperature gauge does not work
- Jerky running
What the fault can affect2
- The module switches itself off (bus-off) and stays off until its power supply is cut
- At the next power-up the module makes new attempts to communicate
General guidance for car owners. Diagnosis on the car can point to a different cause.