P1626: How to Diagnose & Fix — Theft Deterrent Fuel Enable Signal Lost
3 vehicles · 2 makes · $100-$900 repair
How to diagnose and fix P1626: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chevrolet Impala · 2000–2005
The Passlock anti-theft system causes intermittent no-start conditions where the security light comes on and the engine is disabled. The ignition lock cylinder carries a magnet read by a Hall-effect sensor in the lock housing; when the sensor, its wiring, or the BCM connector terminals fail, the BCM detects a mismatch and fuel is locked out. The problem typically worsens progressively from occasional to daily. 225+ complaints were filed for the 2002 model year alone.
Common Symptoms
- Security/theft light flashing on dashboard
- Engine cranks but will not start
- No-start condition occurs more frequently over time
- Car starts after waiting 10+ minutes
- SECURITY telltale illuminated
How to Fix
Per GM guidance for 2000-2005 Impala, first inspect the BCM connectors for damaged or loose/unseated terminals before replacing the BCM, since many replaced BCMs test good. If the Passlock sensor in the ignition lock cylinder/housing is faulty, replace the lock cylinder/sensor assembly and perform the roughly 30-minute Passlock relearn (key on, engine off, until the security light goes out). As a temporary measure, leaving the key on until the security light stops flashing (about 10 minutes) and retrying will often start the car.
Sources for this issue (2)
Pontiac Grand Am · 1999–2005
The Passlock theft-deterrent sensor built into the ignition lock cylinder wears and sends an unstable resistance signal to the body control module, which then interprets a legitimate key as a theft attempt. The system disables the fuel injectors, leaving the car cranking but not starting with the SECURITY light flashing, and the failure typically recurs and worsens until owners are stranded repeatedly. This is one of the most widely documented complaints on the 1999-2005 Grand Am, with a 23+ page Edmunds thread and a RepairPal-confirmed pattern failure.
Common Symptoms
- Engine cranks but won't start
- SECURITY light flashing or stuck on
- Car starts after waiting 10 minutes with key on
- Intermittent no-starts that become more frequent
- Stalling shortly after start-up with security light on
How to Fix
Replace the ignition lock cylinder (which contains the Passlock sensor) and perform the 10-30 minute Passlock relearn procedure. As a stopgap, owners can do the 10-minute relearn (key on, wait for the security light to stop flashing) to start the car; many DIYers permanently bypass the sensor with an inline resistor on the Passlock signal wires.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- ACDelco 19258699 ignition-lock housing with Passlock sensor
Housing/sensor is distinct from the keyed lock cylinder; perform the exact relearn and confirm connector/VIN.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (5)
- 2003 Pontiac Grand Am Passlock Problem, Won't Start And Security Light Is Blinking: 25 Complaintsarticle
- Security light on Pontiac Grand Am — Car Talk Community (2004 Grand Am, Passlock ignition switch failure)forum
- Pontiac Grand Am Security Passlock Problems — Edmunds Car Forums (23+ pages)forum
- No Start Due to Failed Passlock Sensor: Pontiac Grand Am Electrical System — RepairPalarticle
- NHTSA complaints, 2002 Pontiac Grand Am — multiple ODI records for Passlock/security-light no-start (10898347, 10622496, 10503032, 10726457)nhtsa
Chevrolet Corvette · 1997–1999
Early C5s use an electronic Column Lock mechanism as part of the anti-theft system (fitted to 1997-2004 manual cars and 1997-2000 automatics). The mechanism and its electronics fail with age; when the column fails to unlock at key-on the PCM disables fuel and the car will not drive (or displays 'Service Column Lock'/'Pull Key, Wait Ten Seconds' on the DIC). In some cases the column can lock unexpectedly. It is one of the best-known early-C5 gremlins and is the subject of GM service bulletins and a recall/special policy.
Common Symptoms
- No-crank / no-start or limp (~2 mph) condition
- Steering wheel remains locked
- 'Service Column Lock' / 'Pull Key Wait Ten Seconds' DIC message
- Intermittent failure to start
- Column unexpectedly locking
How to Fix
Modern accepted fix is to install an electronic column-lock bypass module or the GM relay fix (removes the failure-prone lock function) rather than sourcing the increasingly scarce factory lock assembly. Note on 1997-1998 cars the GM harness/relay is often more BCM-compatible than some aftermarket bypass modules. A BCM reset (pull the relevant fuse ~10 seconds) can temporarily clear the condition.
Sources for this issue (2)
Find P1626 by make
Browse every documented model and issue for your make.
P1626 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1626 mean?
P1626 stands for "Theft Deterrent Fuel Enable Signal Lost." This is a manufacturer-specific (commonly GM) anti-theft code indicating that the fuel-enable signal from the theft-deterrent system was lost or not received by the engine control module. As a security measure, the immobilizer or body control module must send a valid signal authorizing the ECM to deliver fuel; without it, the ECM disables fueling so a stolen vehicle cannot be driven. The result is usually an engine that cranks but will not start, often with a security light on. It generally points to a security-system communication or authentication problem rather than a fuel or engine mechanical fault.
What are the most common causes of P1626?
The most common causes of P1626 are: Communication fault between the body control module and ECM, Faulty or unrecognized key/transponder or immobilizer issue, Damaged wiring or connectors in the theft-deterrent circuit, Faulty body control module (BCM), Faulty or improperly programmed engine control module, Loss of power or ground to a security-system module, Modules not properly relearned after a battery or part replacement. The specific cause varies by vehicle.
How much does it cost to fix P1626?
Repair costs for P1626 range from $100 to $900, depending on the vehicle and root cause.
Which vehicles are affected by P1626?
Au7o has documented P1626 across 3 vehicle models from 2 manufacturers: Chevrolet, Pontiac.
Join 600+ people using Au7o to better understand their vehicles.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.