What does it mean?
U1451 is a Network (CAN bus, module communications) fault code. It indicates: Data Circuit Message .
Symptoms
- Engine cranks but will not start, or fires and stalls after a second
- Anti-theft indicator flashing rapidly or staying on
- Alarm sounds by itself, or the system will not arm
- Audible warnings and chimes behave incorrectly
- Only one of the vehicle's keys works
- Message on the display that the key is not recognised
Likely causes
- No valid message passing between the anti-theft module and the PCM (Powertrain Control Module)
- Transponder key with a damaged chip, or a key that was never programmed to this vehicle
- Faulty transponder antenna ring around the ignition lock
- Open or shorted wiring between the anti-theft module and the engine controller
- Anti-theft module or engine controller replaced without being matched to each other
- Weak battery or a poor ground causing a module to reset during cranking
- Aftermarket alarm or remote start wired into the immobiliser circuits
How to fix it
- Try every key the vehicle has; if one works, the fault is in the other key, not the system
- Read the anti-theft module and check whether the key is being recognised at all
- Load-test the battery and clean the main grounds before deeper diagnosis
- Inspect the antenna ring around the ignition lock and its connector for damage
- Test the wiring between the anti-theft module and the engine controller for open and short circuits
- Disconnect any aftermarket alarm or remote start system and retest
- Reprogram the keys and match the modules with the correct equipment only as the last step