OBD-II trouble code
B00B1: Driver Seat Occupant Classification Sensor B (Subfault)
The airbag/SRS control module detected a fault with the driver-seat occupant classification sensor B, part of the system that senses the driver's seat occupancy for restraint decisions. Airbag operation may be affected, so this needs prompt professional attention.
Quick facts
- System
- Body
- Category
- Airbag / SRS Restraints
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $900
- DIY difficulty
- Shop recommended
What does B00B1 mean?
B00B1 is a body (B) code stored by the airbag control module. It is a hexadecimal code — the character after B00 is the letter B, not a number — and its SAE-generic definition is 'Driver Seat Occupant Classification Sensor B,' referring to one of the sensors that classify occupancy of the driver's seat within the supplemental restraint system. Occupant classification is most familiar on the passenger side, but some vehicles also sense the driver's seat — for belt-reminder logic, restraint tailoring, or advanced airbag strategies — using seat-mounted weight, pressure, or belt-tension sensors. The 'B' designation indicates the second sensor or channel in that driver-seat set (sensor A being the first). The sensor feeds an occupant-classification function that reports to the main airbag control module.
The module sets B00B1 when driver-seat sensor B reports invalid data or its circuit is out of specification — an open or short in the sensor wiring, a corroded or backed-out connector under the seat, a failed sensor, a mis-calibrated or un-zeroed system, or a faulty classification module. A symptom byte appended to the code narrows down the exact fault. Because the sensor and its wiring live in or under the driver's seat, connectors disturbed by seat travel, floor moisture, spilled liquids, or aftermarket seat-cover and seat-heater work are common trouble spots, and some systems require a zero/recalibration procedure after any seat or sensor service. Confirm the exact configuration against your make's service data, as occupant-sensing designs vary widely and not every vehicle classifies the driver's seat.
This is a supplemental restraint fault, not a driveability fault: the vehicle drives normally, but restraint behavior tied to driver-seat sensing may not perform as designed, and airbag circuits carry a small risk of unintended deployment when mishandled. SRS diagnosis and repair should be performed by a qualified technician who can safely disable the system and run any required calibration, and the fault should not be left unrepaired.
Common causes
- Corroded, backed-out, or loose connector under the driver's seat
- Failed driver-seat occupant classification sensor (weight, pressure, or belt-tension)
- Damaged wiring in the seat harness from seat travel or floor moisture
- System out of calibration or never zeroed after seat/sensor service
- Faulty occupant classification module
- Aftermarket seat covers, heaters, or heavy items on the seat interfering with the sensor
Symptoms
- Airbag / SRS warning light on
- Seat-belt reminder or occupant indicator behaving incorrectly
- Stored B00B1 fault (often with a symptom byte) in the restraints module
- No effect on engine or driving performance
Diagnostic steps
- 1.Use a scan tool that can access the airbag/SRS module and record B00B1 with its full symptom byte and any companion occupant-detection codes.
- 2.Confirm no aftermarket seat cover, seat heater, or heavy item is interfering with the sensor, and remove anything unusual on the driver's seat before testing.
- 3.With the system safely disabled per service procedure, inspect the under-seat connector and seat harness for corrosion, moisture, or backed-out terminals.
- 4.Check driver-seat sensor B's circuit and any module communication against specification to separate a wiring/connector fault from a failed sensor or module.
- 5.If a companion sensor A code is also present, focus on a shared connector, power, or ground rather than two independent sensor failures.
- 6.If the seat, sensor, or module was recently serviced, run the make-specific zero/recalibration procedure, which many systems require.
- 7.Repair the wiring/connector or replace the indicated sensor or module, recalibrate, then clear codes and confirm the SRS light stays off.
Repair cost
$100 – $900
A connector repair or a recalibration can be inexpensive, while a failed seat occupant sensor or classification module is much costlier and often needs calibration. SRS diagnostic time typically runs $100-$200; sensor or module replacement with the required calibration commonly falls in the several-hundred-dollar range. SRS work should be done by a qualified technician.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with airbag / srs crash sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.