What does it mean?
P1628 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Theft Deterrent Fuel Enable Signal Not Received .
Symptoms
- Engine cranks normally but never fires, or fires and then stalls within a couple of seconds
- Security or key symbol lit or flashing in the instrument cluster
- MIL (check engine lamp) on with the stored security code
- No injector pulse during cranking
- Starts sometimes and not others, often worse when cold or with one particular key
- Fuel pump may run normally, which misleads the diagnosis
Likely causes
- Theft deterrent module not sending the fuel enable message, either because of its own fault or because the key was rejected
- Key transponder not learned, damaged or with a weak signal
- Antenna ring at the ignition lock faulty, or its connector loose or corroded
- Open circuit, short or corrosion in the wiring between the theft module and the engine module
- Engine module replaced without being matched to the theft deterrent system
- Low battery voltage during cranking, which can prevent the security handshake completing
- Internal fault in either the theft deterrent module or the engine module
How to fix it
- Try a second known-good key immediately; a working spare narrows the fault down straight away
- Watch the immobilizer status in live data during cranking and see whether the enable signal is reported
- Check for injector pulse and confirm the fuel system is genuinely being disabled rather than starved
- Measure battery voltage during cranking; a low value can block the security handshake
- Inspect the antenna ring and its connector at the ignition lock and separate any spare transponders from the key ring
- Test the wiring between the theft module and the engine module for continuity and shorts
- Re-run the theft system relearn or matching procedure if either module has been replaced