P1626 on Chevrolet: How to Diagnose & Fix
Theft Deterrent Fuel Enable Signal Lost
2 Chevrolet models · 2 documented issues · 2 critical · $100-$900 repair
P1626 on Chevrolet by model: symptoms, diagnosis and fix
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)
Early C5s use an electronic Column Lock mechanism as part of the anti-theft system (across the C5 run, GM fitted it to manual cars built 1997-2004 and automatics built 1997-2000). 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)
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 on a Chevrolet?
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. On Chevrolet it is documented across 2 models: Impala, Corvette.
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 on a Chevrolet?
Published repair estimates on Chevrolet range from $100 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.