B3031: How to Diagnose & Fix — Security System Controller in Learn Mode
4 vehicles · 2 makes · $10-$800 repair
How to diagnose and fix B3031: 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 Malibu · 2000–2005
A common failure on early-2000s Malibu models is the Passlock security system falsely detecting a theft condition, which can disable fuel delivery and prevent the engine from starting. Owners report the SECURITY light flashing, long wait times before restart, and in some cases intermittent stalling or crank-no-start behavior. The root cause is typically failure in the ignition lock cylinder sensor/housing or related wiring causing incorrect resistance/voltage readings to the body control module.
Common Symptoms
- SECURITY light flashing or staying on
- Crank but no start
- Starts after waiting 10 minutes
- Intermittent stalling
- No injector pulse/fuel disable
- Random no-start especially in hot weather
How to Fix
Diagnosis usually starts by checking for SECURITY lamp behavior, BCM-related codes, and verifying Passlock sensor data during crank. Repairs commonly involve replacing the ignition lock cylinder housing/switch assembly, repairing wiring at the column, and performing the Passlock relearn procedure. Some owners also replace the ignition switch if heat-related internal contact failure is present.
Sources for this issue (2)
Chevrolet Silverado 1500 · 1999–2007
The Passlock II theft-deterrent system reads a Hall-effect sensor and magnet in the ignition lock cylinder. As the sensor or lock cylinder wears, the BCM sees an out-of-range voltage, flags a theft fault, flashes the SECURITY light, and disables fuel injection so the engine cranks but won't start. Owners get stranded with a 'Service Theft System' or security light and a no-start that often clears after a wait.
Common Symptoms
- Engine cranks but will not start
- SECURITY / 'Service Theft System' light flashing or lit
- No-start clears after waiting ~10 minutes
- Intermittent stalling just after start
- Theft codes stored in BCM
How to Fix
First try the 10-minute relearn: key to ON, attempt start, then leave key ON until the security light stops flashing (~10 min), key off 5 sec, then start; repeat up to 3 cycles. If it recurs, replace the Passlock sensor or ignition lock cylinder and relearn.
Sources for this issue (3)
Chevrolet Colorado · 2004–2012
First-generation Colorado/Canyon trucks commonly suffer from Passlock-related ignition switch failures that trigger a crank-no-start or start-and-stall condition with the security light illuminated. Owners often report the truck starting normally after a 10-minute relearn wait, then failing again later. GM issued service information on theft deterrent and ignition switch diagnosis, and the issue is widely documented in owner complaints and forums.
Common Symptoms
- crank no start
- starts then stalls
- security light on
- intermittent no start
- must wait 10 minutes before restart
- no injector pulse
How to Fix
Diagnosis includes checking for theft deterrent codes, monitoring the security indicator, and verifying ignition switch/Passlock sensor operation. The usual fix is replacing the ignition switch assembly and performing the relearn procedure; some owners also inspect wiring at the column and battery voltage because low voltage can aggravate the system. If repeated failures continue, the lock cylinder housing and related wiring should be inspected.
Sources for this issue (3)
Pontiac G6 · 2005–2010
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B3031 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 B3031 mean?
B3031 stands for "Security System Controller in Learn Mode." B3031 is a manufacturer-specific body code (common on GM vehicles) indicating the body control module has entered, or is stuck in, the security/anti-theft key learn mode. It is often an informational status rather than a true failure, set automatically while a coded key is being programmed and cleared once learning completes. It only indicates a real fault if the module fails to exit learn mode, which can disable starting and illuminate the security indicator.
What are the most common causes of B3031?
The most common causes of B3031 are: Module currently in normal key-learning procedure (informational), Key programming not completed correctly, Failed key relearn / fewer than required keys learned, Faulty or unrecognized transponder key, BCM software or programming fault, Faulty body control module preventing learn-mode exit. The specific cause varies by vehicle.
How much does it cost to fix B3031?
Repair costs for B3031 range from $10 to $800, depending on the vehicle and root cause.
Which vehicles are affected by B3031?
Au7o has documented B3031 across 4 vehicle models from 2 manufacturers: Chevrolet, Pontiac.
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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.