Theft Deterrent System Fuel Enable Signal Not Received

What it means

This is a GMC manufacturer-specific code, and the same number can mean something different on other makes. The theft deterrent system (Passlock or PASS-Key) sends the engine computer an enable message before fuel injection is allowed, and this code means that message never arrived. The result is usually a no-start or a start-and-stall, and the cause is most often in the lock cylinder, the key itself or battery voltage.

Models covered: GMC models with Passlock/PASS-Key theft deterrent, mainly 1990s–2000s.

Related codes: P0562P0563

Symptoms4

• The engine dies right after starting with the security light on.
• No start in the morning or after sitting, then it starts later.
• Security light flashing on the dash.
• The problem sometimes begins after the battery was replaced or disconnected.

Possible causes6

• A failed Passlock sensor in the lock cylinder or wiring worn by steering column movement.
• A worn key pellet or a non-matching key copy on PASS-Key systems.
• A weak battery or corroded terminals lowering voltage during cranking.
• A worn ignition lock cylinder.
• A communication fault between modules on the Class 2 bus.
• A fault in the body control module (BCM) or theft module, which is less common.

How to diagnose5

1. Check the battery and terminals first, as low voltage causes similar symptoms.
2. Try the original spare key; if the engine starts with it, the first key is the problem.
3. Read body or theft module codes along with the engine computer code.
4. Check the sensor wiring in the steering column while turning the wheel and monitoring.
5. Confirm module communication on the Class 2 bus with a GM-capable scan tool.

How to fix5

1. Repair the battery or its terminals.
2. Use a good original key or replace the damaged key.
3. Perform the timed relearn procedure per the service manual.
4. Repair the sensor wiring or replace the lock cylinder and sensor, then relearn.
5. Clear the codes and test starting several times at different times of day to confirm the code does not return.

A battery, key or relearn keeps the cost low, while a new lock cylinder or a module with programming raises it to the top of the range.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions