B00A0: How to Diagnose & Fix — Occupant Classification System (Subfault)
2 vehicles · 2 makes · $150-$1,200 repair
How to diagnose and fix B00A0: 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 Versa · 2007–2022
The Versa's NISSAN Advanced Air Bag System weighs the front passenger via an occupant classification sensor mat and bladder built into the passenger seat cushion, plus a seat-belt tension sensor. The pressure mat's printed circuit traces crack from repeated seat loading, and the harness that runs under the seat frame chafes or corrodes at the connector. When the OCS control unit sees an implausible or open-circuit reading it fails safe and leaves the 'PASSENGER AIR BAG OFF' telltale illuminated with a normal-sized adult seated — meaning the passenger front airbag will not deploy in a crash. Owners report the light behaving erratically first (going out only when the passenger shifts position) before staying on permanently. Nissan's service remedy is often a re-zero/reflash of the OCS control unit rather than parts, so a good number of cars are fixed without a seat teardown, but a genuinely failed mat requires the seat cushion assembly.
Common Symptoms
- PASSENGER AIR BAG OFF light stays lit with an adult in the seat
- Airbag warning light on in the instrument cluster
- Passenger airbag status light flickers when passenger shifts weight
- Light goes out only if the passenger sits in an unnatural position
- Airbag system stores occupant-sensor fault codes
How to Fix
Do not clear it and ignore it. Have the airbag system scanned for OCS/occupant-sensor codes. First step is inspecting and reseating the connectors under the passenger seat for chafe, corrosion, or a pinched harness from cargo shoved under the seat. If wiring is sound, the dealer performs the OCS control-unit zero-point reset/reprogram, which resolves a large share of cases. If the sensor mat itself is open, the passenger seat cushion assembly with integrated OCS mat must be replaced and the system recalibrated. Bypassing or resistor-spoofing the sensor is discussed on forums but defeats a federally mandated restraint and should not be done.
Sources for this issue (4)
Ford Bronco · 2021–2023
A documented Bronco safety issue involved front seat belt pretensioners that may not deploy properly in a crash. This defect increases injury risk because the restraint system may not tighten the belt as intended during impact. The issue is recall-documented and has been discussed by owners receiving recall notices and dealer repairs.
Common Symptoms
- Recall notice received
- Airbag or seat belt warning light
- Concern about restraint system readiness
- Stored SRS fault codes
How to Fix
Check VIN status for open recall campaigns and have the pretensioner assemblies inspected and replaced by a Ford dealer if applicable. If the airbag light is on, scan the RCM/SRS system for stored faults before replacing components. After repair, confirm the restraint system passes self-test and no warning indicators remain.
Sources for this issue (1)
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B00A0 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 B00A0 mean?
B00A0 stands for "Occupant Classification System (Subfault)." This SRS code refers to a fault in the Occupant Classification System (OCS), which detects the size, weight, and presence of the front passenger (including an empty seat or a child seat) to decide whether and how forcefully the passenger airbag should deploy. The airbag module sets this code when the OCS sensors, weight mat, or related wiring report a fault. With this code active, the passenger airbag may be incorrectly enabled or disabled, so it should be diagnosed for safety.
What are the most common causes of B00A0?
The most common causes of B00A0 are: Faulty occupant classification / weight sensor mat in the seat, Damaged wiring or connector under the passenger seat, OCS module needing recalibration after seat service, Aftermarket seat covers or modifications affecting the sensor, Corroded or loose connector, Faulty OCS or airbag (SRS) control module, Poor ground connection. The specific cause varies by vehicle.
How much does it cost to fix B00A0?
Repair costs for B00A0 range from $150 to $1,200, depending on the vehicle and root cause.
Which vehicles are affected by B00A0?
Au7o has documented B00A0 across 2 vehicle models from 2 manufacturers: Ford, Nissan.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.