What does it mean?
U1147 is a Network (CAN bus, module communications) fault code. It indicates: Additional CAN Interior Bus ECU Detected .
Symptoms
- The fault reappears as soon as it is cleared, with no driver complaint in some cases
- Warning messages on the display that cannot be reset
- Individual comfort or infotainment functions working erratically
- Other modules storing communication faults at the same time
- Slow module wake-up or the network staying awake and draining the battery
Likely causes
- Aftermarket equipment connected to the interior bus, such as an alarm, telematics box, amplifier or auxiliary heater controller
- A second hand module fitted from a different vehicle with a different variant identifier
- Interior equipment retrofitted without updating the vehicle configuration or gateway list
- Two units answering on the same bus address after an incorrect coding attempt
- Vehicle configuration data not restored after a gateway or body module replacement
- Coding or programming interrupted by low battery voltage
- Improper wiring taps made into the interior bus during accessory fitment
How to fix it
- Read the installed unit list with a scan tool and check it against the original vehicle configuration
- Determine which unit is not supposed to be there, considering any recently fitted accessories
- Unplug aftermarket devices connected to the interior bus and check whether the code stops returning
- If a module was replaced, verify that it is the right variant for this vehicle and that it has been coded properly
- Inspect the point where any accessory was spliced into the bus, and remove improper taps
- Ensure battery voltage is stable, then repeat the configuration or coding procedure so the gateway rebuilds its list
- Clear the codes and confirm the configuration holds over several ignition cycles