What does it mean?
P1629 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Theft Deterrent Fuel Enable Signal Not Received .
Symptoms
- Engine cranks strongly but will not run, or catches and dies almost immediately
- Security or key warning lamp on or flashing
- MIL (check engine lamp) on with the stored code
- Injectors not pulsing while the fuel pump may still prime normally
- Fault often intermittent: the vehicle starts on some attempts and not on others
- Symptoms worse in damp weather or after washing the vehicle
Likely causes
- Wiring between the theft deterrent module and the engine module open, shorted or corroded
- Poor ground or unstable supply at the theft deterrent module causing it to reset mid-handshake
- Key transponder not read: faulty antenna ring, damaged key or an unlearned key
- Engine module or theft module replaced and never matched to each other
- Data bus fault so the enable message never crosses the network
- Corroded connectors behind the steering column, a common damp-weather failure
- Internal failure of the theft deterrent module
How to fix it
- Try a second key and note whether behaviour changes
- Read both modules and establish which one reports the missing authorisation
- Check the theft deterrent module supply and ground with a voltage-drop test, especially during cranking
- Test the enable line or bus connection between the two modules for continuity, short to ground and short to battery
- Inspect connectors around the steering column and under the dash for damp and green corrosion
- Confirm both modules are matched to the vehicle and re-run the matching procedure if anything has been replaced
- Repair the wiring first; replace and code a module only after the circuit and the key have been proven