B2960: How to Diagnose & Fix — Key/Immobilizer Communication Error
8 vehicles · 2 makes · $10-$800 repair
How to diagnose and fix B2960: 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 flashes and the fuel pump is disabled. The ignition lock cylinder contains a Hall-effect sensor that reads a resistance value; when contacts wear or corrode, the BCM detects a mismatch and locks out fuel delivery. 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
Sources for this issue (1)
Chevrolet Cavalier · 2000–2005
The Passlock security system frequently malfunctions, reading the wrong resistance from the ignition cylinder sensor and refusing to allow the engine to start. The security light flashes and the car cranks but will not fire. This commonly occurs in cold weather or after the ignition cylinder wears internally.
Common Symptoms
- Engine cranks but will not start
- Security light flashing on dash
- Intermittent no-start condition
- Problem worse in cold weather
How to Fix
The temporary fix is to turn the key to ON (not start), wait 10 minutes for the security light to stop flashing, then turn off and restart. The permanent fix is to bypass the Passlock sensor by wiring a 2.2K ohm resistor in place of the hall-effect sensor in the ignition cylinder. Some owners replace the entire ignition lock cylinder assembly.
Sources for this issue (1)
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 (1)
Chevrolet HHR · 2006–2011
Chevrolet Malibu · 2000–2005
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B2960 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 B2960 mean?
B2960 stands for "Key/Immobilizer Communication Error." B2960 is a body/security code indicating a key or immobilizer (anti-theft) communication error, where the security module read sensor or key data that appears valid in form but does not match the expected, previously learned value. On many vehicles this involves a Passlock or transponder/immobilizer check that must pass before the computer allows the engine to start. When it fails, you typically get a security/anti-theft warning light and a no-start or no-crank condition. This is a manufacturer-specific code tied to the theft-deterrent system rather than an engine mechanical fault.
What are the most common causes of B2960?
The most common causes of B2960 are: Faulty Passlock/ignition lock cylinder sensor, Damaged or worn transponder key or key chip, Wiring or connector fault in the security sensor circuit, Body control module (BCM) failure or needs relearn, Incomplete or lost immobilizer/key relearn procedure, Worn ignition lock cylinder, Aftermarket alarm or remote-start interference. The specific cause varies by vehicle.
How much does it cost to fix B2960?
Repair costs for B2960 range from $10 to $800, depending on the vehicle and root cause.
Which vehicles are affected by B2960?
Au7o has documented B2960 across 8 vehicle models from 2 manufacturers: Chevrolet, Pontiac.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.