What does it mean?
U1151 is a Network (CAN bus, module communications) fault code. It indicates: No Communication With Vehicle Interface Unit .
Symptoms
- Auxiliary and connected features controlled through the interface stop working
- Warning or information messages about a system not being available
- Scan tool cannot reach the interface unit, and sometimes other modules behind it
- Functions that worked when the vehicle was cold fail once it warms up, or the other way round
- Battery drain when the unit keeps the network awake
- The code returns shortly after being cleared
Likely causes
- Blown fuse or an open power feed to the interface unit
- Loose, corroded or partly unlatched connector at the unit
- Open or shorted bus wiring between the interface unit and the gateway or body control module
- Poor ground at the unit mounting point, often behind a trim panel or under a seat
- Water reaching the unit after a leak, a blocked drain or a spill
- Interface unit replaced without being coded and configured, or an internal failure
- Aftermarket equipment connected to the interface wiring and disturbing the bus
How to fix it
- Scan all modules to see whether only this unit is missing or a whole branch has gone quiet
- Check the fuse and measure supply voltage and ground at the interface unit connector with the circuit loaded
- Remove the trim and inspect the unit and connector for water marks, corrosion and damaged pins
- Measure the bus lines at the unit and compare them against a module that is communicating normally
- Test the wiring between the unit and the gateway for opens, shorts and high resistance
- Disconnect any aftermarket equipment attached to this circuit and retest
- Replace the interface unit last, and complete the coding or configuration it requires