OBD-II trouble code
B00C0: Passenger Seat Occupant Classification Sensor A (Subfault)
The airbag/SRS control module detected a fault with the passenger-seat occupant classification sensor A — part of the system that senses who is in the passenger seat to decide how the passenger airbag should deploy. 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 B00C0 mean?
B00C0 is a body (B) code stored by the airbag control module. It is a hexadecimal code — the character after B00 is the letter C, not a number — and its SAE-generic definition is 'Passenger Seat Occupant Classification Sensor A,' referring to one of the sensors that classify occupancy of the front passenger seat within the supplemental restraint system. The Occupant Classification System (OCS) uses seat-mounted weight, pressure, or belt-tension sensors to decide whether the passenger seat holds an adult, a small occupant, a child seat, or is empty — and therefore whether and how forcefully the passenger airbag should deploy. This is what drives the familiar 'passenger airbag ON/OFF' indicator. The 'A' designation indicates the first sensor or channel in that passenger-seat set, with sensor B (code B00C1) being the second.
The module sets B00C0 when passenger-seat sensor A 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 passenger seat, connectors disturbed by seat travel, floor moisture, spilled liquids, or aftermarket seat-cover and seat-heater work are common trouble spots, and many OCS systems require a zero/recalibration procedure after any seat or sensor service. If both B00C0 and B00C1 are stored, the two passenger-seat sensor circuits often share a connector, power, or ground, so a single shared fault is more likely than two dead sensors.
This is a supplemental restraint fault, not a driveability fault: the car drives normally, but with the classification data invalid the system may suppress or mis-tailor the passenger airbag as a fail-safe, so the 'passenger airbag OFF' indicator may stay lit. Airbag circuits carry a small risk of unintended deployment when mishandled, so SRS diagnosis, repair, and OCS recalibration should be left to a qualified technician, and the fault should not be left unrepaired. Confirm the exact configuration against your make's service data, as occupant-sensing designs vary widely.
Common causes
- Corroded, backed-out, or loose connector under the passenger seat
- Failed passenger-seat occupant classification sensor (weight, pressure, or bladder/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 (OCSM)
- Aftermarket seat covers, heaters, or heavy items on the seat interfering with the sensor
Symptoms
- Airbag / SRS warning light on
- Passenger airbag ON/OFF indicator behaving incorrectly or stuck OFF
- Stored B00C0 fault (often with a symptom byte) in the restraints/occupant module
- Possible companion B00C1 (passenger-seat sensor B) stored alongside it
- No effect on engine or driving performance
Diagnostic steps
- 1.Use a scan tool that can access the airbag/SRS or occupant-classification module and record B00C0 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 passenger seat, and remove anything unusual 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 passenger-seat sensor A'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 B code (B00C1) 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 OCS 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 and passenger-airbag indicator behave correctly.
Repair cost
$100 – $900
A connector repair or an OCS recalibration can be inexpensive, while a failed occupant-classification sensor or module is much costlier and almost always needs calibration afterward. SRS diagnostic time typically runs $100-$200; sensor or module replacement with the required calibration commonly falls in the several-hundred-dollar range. SRS/OCS 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.