What does it mean?
U2101 is a Network (CAN bus, module communications) fault code. It indicates: Control Module Configuration Incompatible .
Symptoms
- Warning lamps and messages appearing after a module change or a retrofit
- Some functions work while others handled by the same module do not
- Scan tool reports a configuration mismatch
- Vehicle runs in a restricted mode or refuses to start
- Convenience features behave as if fitted to a different model
- The code returns immediately after clearing
Likely causes
- Module fitted from a different model, engine variant or equipment level
- Software version in the module not compatible with the other modules on the network
- Configuration data written incorrectly during a previous coding session
- Optional equipment added or removed without the vehicle configuration being updated
- Gateway module still holding an old vehicle option list
- Interrupted programming leaving a mixed set of data inside the module
- Refurbished or non-genuine module carrying wrong internal data
How to fix it
- Compare the module part number and software level with the specification for this exact vehicle
- Check the vehicle option list stored in the gateway against the equipment actually fitted
- Correct the coding with the proper equipment and a stable supply voltage
- If a used module was fitted, confirm whether it can be recoded for this vehicle at all
- Bring all modules that must work together to matching software levels
- Repeat any interrupted programming session from the beginning
- Fit the correct module for the vehicle when recoding is not possible