P1626
Theft Deterrent Fuel Enable Signal Not Received
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The P1626 code is a GM-specific code that means the Powertrain Control Module (PCM) is not receiving the required 'fuel enable' signal from the theft deterrent system. On GM vehicles, the Body Control Module (BCM) must verify that the correct key is being used before it sends a signal to the PCM allowing fuel delivery. Without this signal, the PCM will not allow the engine to run.
This code is extremely common on GM vehicles from the late 1990s through 2000s that use the Passlock or VATS anti-theft systems. The Passlock sensor inside the ignition lock cylinder is the most frequent failure point. A common DIY workaround is the '10-minute relearn' procedure: turn the key to the ON position (don't start), wait 10 minutes until the security light stops flashing, turn the key off, and repeat two more times before starting.
If the relearn procedure doesn't work, the Passlock sensor or entire lock cylinder assembly usually needs replacement. Some owners opt for a Passlock bypass module, which eliminates the sensor from the circuit entirely. While the vehicle may intermittently start and run normally with this code, the no-start condition can leave you stranded, so this should be repaired promptly.
Severity
Symptoms
- •Engine cranks but will not start, or starts and immediately stalls
- •Security or theft deterrent warning light stays on or flashes
- •Intermittent no-start conditions that may resolve temporarily
- •Vehicle starts normally sometimes but fails to start other times
- •No other apparent electrical issues in the vehicle
Likely Causes
The Passlock theft deterrent sensor inside the ignition lock cylinder has failed or is reading the wrong resistance value. This is the most common cause of P1626 on GM vehicles with Passlock systems.
On GM vehicles with VATS (Vehicle Anti-Theft System), the resistor pellet embedded in the key has worn down or the contacts in the lock cylinder that read it are dirty or worn.
The Body Control Module sends a fuel enable signal to the PCM when it recognizes the correct key. A wiring issue or data bus problem between these two modules prevents the signal from being received.
The BCM itself has failed and is unable to generate the fuel enable signal even when the correct key is present.
The electrical portion of the ignition switch has an intermittent fault that prevents the BCM from properly sensing the key-on condition.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the Passlock sensor or ignition lock cylinder assembly
- Perform the Passlock relearn procedure (10-minute key cycle method)
- Replace a worn VATS key or clean the key contacts in the cylinder
- Inspect and repair wiring between the BCM and PCM
- Replace the BCM if other causes are ruled out