OBD-II Code P1626 — What It Means & How to Fix It

What Does This Error Mean?

P1626 is a General Motors-specific code meaning Theft Deterrent Fuel Enable Signal Not Received. The PCM sends a security challenge to the Body Control Module (BCM) or PASS-Key module on startup. The module must reply with the correct authorization before the PCM enables fuel injection. When the PCM does not receive this fuel-enable signal, it disables the fuel system and the engine will not run. This is a security system (anti-theft) fault — the car will crank but not start.

Affected Models

Common in Chevrolet Silverado, Impala, and Malibu
Common in GMC Sierra and Yukon
Common in Pontiac Grand Prix and Bonneville
Seen in Buick LeSabre and Park Avenue with PASS-Key or PASS-Lock systems

Common Causes

PASS-Lock or PASS-Key sensor failure in the ignition cylinder — worn resistor pellet on the key or failing cylinder sensor
Faulty Body Control Module (BCM) — cannot send the correct fuel-enable code to the PCM
Communication fault between the BCM and PCM (CLASS 2 or LAN bus wiring fault)
Low battery voltage preventing normal security handshake from completing
PCM internal fault preventing it from receiving or recognizing the security signal

How to Fix It

Check the theft deterrent indicator (padlock symbol) on the dashboard. If it is flashing or solid, the security system has triggered.

A solid or flashing security light confirms the anti-theft system is preventing the engine from starting.
Try the GM 10-minute relearn procedure: turn the key to ON, wait for the security light to stop flashing (about 10 minutes), then turn off. Repeat two more times. Then start normally.

This procedure can reset a PASS-Lock fault temporarily. It takes 30 minutes total but is free and often works.
Inspect the ignition lock cylinder wiring connector for corrosion or damaged pins.

The PASS-Lock sensor connector is located on the back of the ignition cylinder — a common corrosion point.
Check battery voltage and clean battery terminals. A voltage drop during cranking can disrupt the security handshake.

Low battery voltage is a frequently overlooked cause of security system misfires on GM vehicles.
Have the BCM and PCM inspected at a GM dealer with a Tech 2 scanner for security system faults.

Module-level diagnosis and reprogramming requires dealer-level equipment — standard scan tools cannot access GM security systems.

When to Call a Professional

PASS-Lock sensor replacement in the ignition cylinder is $50 to $150 in parts. BCM programming at a dealer is $100 to $200 for programming labor. PCM replacement and programming is $200 to $600. GM dealer with a Tech 2 or GDS scanner is strongly recommended for this diagnosis.

Frequently Asked Questions

My GM vehicle cranks but won't start and shows a security light — is this P1626?

Very likely yes. P1626 and related PASS-Key/PASS-Lock faults are the most common cause of a crank-no-start with a security light on GM vehicles. The engine cranks because the starter is not part of the security system — only the fuel injectors are disabled.

Is the 10-minute relearn procedure a permanent fix?

It is a temporary workaround, not a permanent fix. If the PASS-Lock sensor is failing, the fault will return. The relearn buys you time to get the vehicle to a shop. For a permanent fix, the ignition cylinder sensor or related module needs to be replaced and reprogrammed.

Can I bypass the GM PASS-Lock system?

There are resistor-based bypasses available, but they defeat the anti-theft system entirely. Bypass modules are sold by security companies for legitimate purposes like remote start installation. They are not a proper repair and may affect insurance coverage. Professional repair is the correct solution.