What does it mean?
U1148 is a Network (CAN bus, module communications) fault code. It indicates: Additional CAN C Bus ECU Detected .
Symptoms
- The code returns immediately after clearing and cannot be erased permanently
- Warning lamps illuminated with no matching drivability fault
- Occasional communication dropouts affecting powertrain or chassis functions
- Rough running, limp mode or transmission faults if the extra device interferes with bus traffic
- Additional communication codes stored in several powertrain modules
Likely causes
- Aftermarket device connected to the powertrain bus, such as a tuning box, data logger, trailer controller or tracking unit
- A replacement engine, transmission or chassis module of the wrong variant, or one taken from another vehicle
- Vehicle configuration not updated after a retrofit or a module change
- Duplicate bus addresses after an incorrect coding session
- Gateway module holding an outdated list of installed control units
- Programming interrupted by low battery voltage or a lost connection
- Poor quality wiring taps made into the high-speed bus
How to fix it
- Read the module list with a scan tool and compare it with the vehicle configuration data
- Ask about and look for aftermarket devices spliced into the powertrain bus, including tuning and tracking equipment, then remove them and retest
- If a module was replaced, confirm that the part number and variant are correct for this vehicle
- Inspect the wiring where any accessory has been tapped into the bus and remove improper joints, restoring the twisted pair
- Confirm stable battery voltage and repeat the coding or configuration procedure
- Check that the gateway module has an up to date list of installed control units
- Clear the codes and verify the network configuration is accepted over several ignition cycles and a road test