What does it mean?
U1108 is a Network (CAN bus, module communications) fault code. It indicates: Additional CAN B ECU Detected .
Symptoms
- The code returns immediately after being cleared, even with no drivability complaint
- Warning lamps or information messages that cannot be reset
- Individual comfort functions behave unpredictably or stop working
- Other modules store their own communication codes at the same time
- Longer than normal wake-up time when the vehicle is unlocked
Likely causes
- Retrofitted or added equipment hung on the body bus, such as an alarm, amplifier, trailer module or telematics box
- A used module taken from another vehicle that carries a different identifier or variant
- Vehicle configuration or variant coding not updated after a repair, retrofit or module replacement
- Two modules answering on the same address after an incorrect coding session
- Gateway module holding an outdated list of installed control units
- A programming session interrupted by low battery voltage and never completed
How to fix it
- Read the installed module list with the scan tool and compare it against the vehicle build configuration
- Identify which unit is extra, paying attention to recently fitted accessories
- Disconnect any aftermarket device wired into the body bus and see whether the code stops returning
- If a module was replaced, check that it is the correct variant and that it was coded to this vehicle
- Check the battery and charging system, then repeat the coding or configuration procedure so the gateway rebuilds its module list
- Inspect the connector where the extra device was spliced in, since improper taps also disturb the bus
- Clear the codes and confirm the network configuration is accepted after several ignition cycles