Failed passenger seat occupant position sensor (the 'C' sensor or sensor element).; Damaged or chafed wiring harness under the passenger seat, often from seat movement or cargo.; Loose, corroded, or disconnected electrical connector at the sensor or module.; Faulty occupant detection module or body control module processing the sensor signal.; Seat cushion or track damage that misaligns the sensor or its mounting.; Aftermarket seat covers or heavy objects on the seat interfering with sensor calibration.

DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B00C9

B00C9Passenger Seat Occupant Position Sensor C

Q: What does code B00C9 mean?

Passenger Seat Occupant Position Sensor C. B00C9 indicates that the body control module or occupant detection module has detected a fault in the passenger seat occupant position sensor circuit, specifically the 'C' sensor or circuit leg. The computer monitors the sensor's signal voltage or resistance and sets this code when the reading falls outside the expected range or the circuit fails a continuity check.

B00C9 indicates that the body control module or occupant detection module has detected a fault in the passenger seat occupant position sensor circuit, specifically the 'C' sensor or circuit leg. The computer monitors the sensor's signal voltage or resistance and sets this code when the reading falls outside the expected range or the circuit fails a continuity check.

SystemBody

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The airbag warning light or passenger airbag status indicator illuminates or flashes.
The passenger airbag may be automatically disabled even when an adult occupies the seat.
A warning message such as 'Passenger Airbag Off' appears on the dashboard.
Often no symptoms besides the warning light, with the seat belt reminder and airbag system otherwise functioning normally.
In some vehicles, the seat belt chime may not activate for the passenger seat.
Intermittent warning light operation when the passenger seat is moved or adjusted.

Common causes, most likely first

Failed passenger seat occupant position sensor (the 'C' sensor or sensor element).
Damaged or chafed wiring harness under the passenger seat, often from seat movement or cargo.
Loose, corroded, or disconnected electrical connector at the sensor or module.
Faulty occupant detection module or body control module processing the sensor signal.
Seat cushion or track damage that misaligns the sensor or its mounting.
Aftermarket seat covers or heavy objects on the seat interfering with sensor calibration.

How to diagnose and fix it

Inspect the under-seat wiring harness and connectors for damage, corrosion, or loose pins; repair or reseat as needed.
Check the sensor mounting and seat cushion for physical damage or obstruction; correct any misalignment.
Use a scan tool to read live data from the occupant position sensor and compare against specifications.
Perform a resistance or voltage check on the sensor circuit at the connector to isolate the sensor from the wiring.
If the sensor signal is out of range, replace the passenger seat occupant position sensor and recalibrate the occupant detection system.
Clear the code and verify the repair by cycling the ignition and confirming the airbag status indicator operates correctly.
If the fault persists, diagnose the occupant detection module or body control module and replace if faulty.

Before you replace the occupant sensor

A common oversight is a loose connector or chafed wire under the passenger seat caused by seat adjustment or items stored beneath it, which mimics a failed sensor.
Aftermarket seat covers or heavy objects left on the passenger seat can alter sensor readings and set this code without any component failure.
The code does not always mean the sensor itself is bad; the occupant detection module or body control module can misinterpret a good signal and store the code.
On some vehicles, a weak or failing battery can cause erratic sensor voltages and set this code along with other body codes.
Replacing the sensor without recalibrating the occupant detection system often leads to the code returning or the airbag system remaining disabled.

Can I keep driving with B00C9?

The vehicle remains safe to drive in most cases, but the passenger airbag may be disabled, reducing protection for a front passenger. Avoid carrying a passenger in the front seat until the fault is repaired, and have the system diagnosed promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.