What does it mean?
U1207 is a Network (CAN bus, module communications) fault code. It indicates: Manufacturer-Specific CAN/Network Bus Fault . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- Several unrelated warning lamps on at the same time
- A group of convenience features stops working together — locks, windows, lighting, cluster gauges
- Scan tool cannot see one or more modules
- Gauges sweep, freeze or drop to zero
- Intermittent no-start, or accessories that stay live after the key is removed
- Battery goes flat overnight because a module never goes to sleep
Likely causes
- A module stops transmitting because it has lost its power feed or its ground
- Open circuit or high resistance at a splice in the bus wiring, a common failure inside splice packs
- Bus wire shorted to ground or to battery positive, pulling the whole network down
- Corroded, wet or spread terminals at a module connector or at the diagnostic connector
- A module fitted from another vehicle, or replaced and never configured, reporting the wrong identifier
- A failed module that keeps transmitting corrupt data and jams the network
- Weak battery or a charging fault causing modules to reset during cranking
How to fix it
- Run a full module scan and list which modules answer and which do not
- Load-test the battery and clean the main ground points before chasing anything on the network
- Measure power and ground at the missing module before doing anything else
- Inspect the bus wiring and splice packs for corrosion, chafing and pinched sections
- Unplug modules one at a time to find one that is loading or jamming the bus
- Verify that any replaced module has been configured and identified correctly for this vehicle
- Repair the harness with soldered, sealed joints; replace a module only after all of the above checks out