What does it mean?
U1117 is a Network (CAN bus, module communications) fault code. It indicates: Immobilizer-ECU Timeout .
Symptoms
- Engine cranks but does not start, or fires briefly and stalls after one or two seconds
- Immobilizer or key symbol flashing or staying lit in the cluster
- Intermittent no-start that clears when a spare key is used
- Remote locking or keyless functions behaving unpredictably
- The immobilizer unit is missing from the scan tool module list
Likely causes
- Damaged or unplugged antenna ring around the ignition lock, or a broken lead from the ring to the immobilizer unit
- Poor power feed, blown fuse or bad ground at the immobilizer control unit
- Open or shorted data line between the immobilizer unit and the engine control or body control module
- Weak battery or heavy voltage drop during cranking, which is a common trigger for this timeout
- Key transponder damaged, or a key that has lost its stored data
- Immobilizer unit or key programming not completed after a module, lock or key replacement
- Corroded connector in the steering column harness
How to fix it
- Try the spare key; if the vehicle starts, focus on the first key transponder rather than the network
- Measure battery voltage during cranking, because voltage collapse alone can produce this timeout
- Remove the steering column shroud and inspect the antenna ring, its lead and connector for damage or disconnection
- Check fuse, supply voltage and ground at the immobilizer control unit under load
- Test the data line between the immobilizer unit and the engine or body control module for continuity and shorts
- Read immobilizer live data and status with the scan tool to see whether the key is being recognised at all
- If any part of the immobilizer chain was replaced, carry out the correct key and module programming procedure before condemning hardware