B2191: How to Diagnose & Fix — Manufacturer-Specific Body Code (Nissan/Infiniti: Difference of Key / NATS ID Mismatch)
2 vehicles · 2 makes · $600-$1,800 repair
How to diagnose and fix B2191: 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.
Nissan Rogue · 2008–2013
A documented no-start condition on push-button-start Rogues can occur when the electronic steering column lock (ESCL/steering lock unit) fails and the vehicle will not transition to READY/ON normally. Owners report the key fob is recognized but the ignition stays stuck, often with a steering lock warning or inability to turn the vehicle on. Nissan issued service information and extended coverage on related steering lock failures across Nissan platforms, and owner complaints/forum reports include Rogue vehicles in this generation.
Common Symptoms
- Vehicle will not start with push button
- Key fob recognized but ignition does not turn on normally
- Steering lock warning or security indicator illuminated
- Intermittent no-start that becomes permanent
- Need to repeatedly press start button before vehicle responds
How to Fix
Diagnosis typically includes confirming battery condition, checking Intelligent Key operation, and scanning BCM/IPDM/steering lock related data for lock status. Repair usually involves replacing the steering lock assembly and performing initialization/reprogramming as required; in some cases the lock is bypassed or a fuse workaround is discussed by owners, but proper repair is replacement and registration of the unit.
Owner tips & cautions
- TipOwners commonly recommend scanning BCM data with a Nissan-capable scan tool to confirm steering lock status before replacing parts.
Infiniti QX50 · 2014–2016
Infiniti/Nissan vehicles using the electronic steering column lock system have a well-documented failure mode where the vehicle will not recognize the lock state, leaving the car unable to start even though the battery and key fob appear normal. The issue is widely discussed across Nissan/Infiniti owner communities and tied to the steering lock control unit used on related FM-platform vehicles. Owners typically report a sudden no-start with the steering wheel locked or the ignition staying in ACC/ON behavior without cranking.
Common Symptoms
- push-button start does nothing
- vehicle stuck in ACC or ON mode
- steering remains locked
- intelligent key warning
- intermittent no-start that becomes permanent
How to Fix
Confirm battery voltage and key fob operation first, then scan BCM/IPDM/steering lock modules for communication or lock-status faults. Repair usually involves replacing or bypassing the failed electronic steering lock assembly depending on model applicability and local repair practice, followed by key/immobilizer relearn if required. Because symptoms mimic a weak battery or bad brake switch, proper diagnosis is important before replacing parts.
Owner tips & cautions
- TipBefore condemning the steering lock, verify the 12V battery is fully charged and load-tested; low voltage can trigger misleading intelligent-key and lock errors.
- TipIf the vehicle intermittently fails to start, scan BCM and immobilizer modules immediately while the fault is active; stored history can disappear after battery disconnects.
Sources for this issue (1)
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B2191 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 B2191 mean?
B2191 stands for "Manufacturer-Specific Body Code (Nissan/Infiniti: Difference of Key / NATS ID Mismatch)." B2191 is a manufacturer-specific body code. On Nissan and Infiniti vehicles it generally means 'Difference of Key' — the body control module and the NATS Intelligent Key failed ID verification, so the key the system read does not match a registered key. As a security/anti-theft fault, the immobilizer may prevent the engine from starting or the steering lock from releasing. On other makes the meaning could differ, so confirm against the specific service data.
What are the most common causes of B2191?
The most common causes of B2191 are: Unregistered or incorrect key/transponder being used, Faulty Intelligent Key or transponder, Wiring fault between key slot/antenna and BCM, Failed key-slot or antenna amplifier, Body control module (BCM/NATS) fault, Interference or low key battery. The specific cause varies by vehicle.
How much does it cost to fix B2191?
Repair costs for B2191 range from $600 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by B2191?
Au7o has documented B2191 across 2 vehicle models from 2 manufacturers: Infiniti, Nissan.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.