Chevrolet P1626 Code: Theft Deterrent Fuel Enable Signal Not Received
The engine computer lost the 'OK to fuel' signal from the Chevy anti-theft system, so it may start and stall.
At a glance
Severity: Moderate
- Meaning
- Theft Deterrent Fuel Enable Signal Not Received
- System
- ECU & Outputs · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $0–$800
- DIY difficulty
- Moderate
On Chevrolets with GM's Passlock system (a sensor in the ignition lock cylinder, common on S-10, Blazer, Cavalier, Malibu, Impala and Monte Carlo from the late 1990s to the mid-2000s) or the older PassKey resistor-pellet key, the anti-theft module or BCM checks the key or cylinder and then sends a fuel enable signal to the PCM. P1626 means that signal was missing or corrupted. Timing decides what you notice: if it drops out after the engine is already running, the car usually keeps going and just stores the code; if it's missing at start-up, the PCM cuts the injectors and the engine starts and dies after a second or two, or won't fire at all, often with the security light on or flashing. Broken Passlock sensor wires in the steering column are a classic cause.
Can I keep driving? If the engine runs, you can drive it, but it may not restart after you shut it off, so avoid parking somewhere you can't be stranded. Get it diagnosed before a trip.
How to read P1626
- P Powertrain
- 1 Manufacturer-specific
- 6 Computer & outputs
- 26 Specific fault
Symptoms
- Engine starts and immediately dies, then repeats
- Security or theft light on or flashing on the dash
- Cranks but doesn't fire after sitting
- Code stored while driving with no symptom at the time
- Intermittent no-starts that come and go with temperature or turning the key
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failing Passlock sensor or broken sensor wires inside the steering column
- Worn ignition lock cylinder or switch disturbing the Passlock signal
- Worn key with a bad resistor pellet or dirty key contacts (PassKey vehicles)
- Low battery voltage or poor grounds during cranking confusing the modules
- Open or shorted fuel enable / serial data wiring between BCM and PCM
- Body control module or theft deterrent module fault
Diagnosis step by step
Check battery and codes in both modules
Charge or test the battery first; weak cranking voltage can trigger theft codes. Then read codes from the PCM and the BCM or theft module; a BCM code for the Passlock sensor narrows it down quickly.
Tools: Multimeter, OBD-II scanner
Watch the security light
Note what the security light does when you turn the key: steady or flashing after a failed start means the system has locked out fuel. A light that stays off while the car still stalls points more toward a fuel or ignition problem.
Try the relearn procedure
Turn the key to ON (don't crank) and leave it until the security light goes out, usually about 10 minutes. Turn the key off for 5 seconds, then start. Some models need this cycle repeated three times. If the car starts, it confirms the theft system was the blocker, but a failing sensor may make the problem return.
Check the PassKey pellet (resistor keys)
On PassKey vehicles, measure the resistance of the key pellet and compare it with the value your system expects, checking for dirt on the key or lock contacts. A reading of open or very erratic means a new key is needed.
Tools: Multimeter
Inspect column wiring
With the lower column trim removed, inspect the Passlock sensor harness where it runs along the lock cylinder. Wiggle it while watching the security light or BCM data; flickering or a fault code change confirms a broken wire.
Tools: Screwdriver, Flashlight
Replace the faulty part and relearn
Replace the Passlock sensor, lock cylinder or key as indicated, then perform the relearn so the BCM and PCM agree again. Verify several restarts, hot and cold.
Tools: OBD-II scanner
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Theft system relearn (10–30 minutes) | Yes | $0–$100 |
| Repair Passlock sensor wiring in the column | No | $100–$300 |
| Replace Passlock sensor or lock cylinder | No | $150–$500 |
| New PassKey key cut and matched | No | $40–$150 |
| Replace and program BCM | No | $300–$800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Depends
P1626 is an anti-theft fault, not an emissions fault. If it's stored without the check engine light on, a US OBD test normally passes; if the light is on at the station, the car fails until it's cleared and the monitors are ready.
Frequently asked questions
Why does my Chevy start and then die immediately?
The PCM lets the engine start, then cuts the fuel injectors when it doesn't get the anti-theft fuel enable signal. It's the system working as designed; the problem is that it no longer recognizes your key or cylinder.
Does the 10-minute relearn fix P1626 permanently?
Only if the fault was a one-time communication loss. If the Passlock sensor or its wires are failing, the no-start will return, and the sensor or cylinder needs to be replaced.
Can a weak battery cause P1626?
Yes. Low voltage during cranking can make the modules miss or garble the signal. Always test and charge the battery before replacing theft system parts.
Is there a way to bypass Passlock?
Bypass modules exist, but they defeat your anti-theft protection and can cause insurance issues. Repairing the sensor or wiring and relearning is the proper fix.
Sources
- Manufacturer public service information (cross-checked)
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy