Faulty passenger seat weight sensor or occupant classification sensor mat.; Damaged or pinched wiring under the passenger seat, often from seat movement.; Corroded or loose electrical connector at the occupant detection module or seat sensor.; Failed passenger occupant detection system control module.; Software calibration error or lost learned values in the occupant detection system.; Aftermarket seat covers or heavy objects left on the passenger seat interfering with sensor readings.

DTC codes / B01xx · Airbags, seats, doors, lights and comfort systems / B0128

B0128Passenger Occupant Detection System Malfunction

Q: What does code B0128 mean?

Passenger Occupant Detection System Malfunction. B0128 indicates that the Passenger Occupant Detection System (PODS) has reported a fault to the airbag control module, meaning the system cannot reliably determine whether a passenger is present or how much they weigh. The computer has detected an electrical or communication problem within the occupant classification circuit, which may prevent the passenger airbag from deploying or cause it to deploy with incorrect force.

B0128 indicates that the Passenger Occupant Detection System (PODS) has reported a fault to the airbag control module, meaning the system cannot reliably determine whether a passenger is present or how much they weigh. The computer has detected an electrical or communication problem within the occupant classification circuit, which may prevent the passenger airbag from deploying or cause it to deploy with incorrect force.

SystemBody

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The airbag warning light on the dashboard stays illuminated.
A message such as 'Passenger Airbag Off' may appear even when an adult is seated.
The passenger airbag status indicator may show 'Off' regardless of seat occupancy.
The seatbelt reminder chime may not activate for the passenger seat.
Often no symptoms besides the warning light, with the system otherwise appearing normal.

Common causes, most likely first

Faulty passenger seat weight sensor or occupant classification sensor mat.
Damaged or pinched wiring under the passenger seat, often from seat movement.
Corroded or loose electrical connector at the occupant detection module or seat sensor.
Failed passenger occupant detection system control module.
Software calibration error or lost learned values in the occupant detection system.
Aftermarket seat covers or heavy objects left on the passenger seat interfering with sensor readings.

How to diagnose and fix it

Inspect the passenger seat area for aftermarket accessories or heavy items and remove them, then clear the code and retest.
Visually inspect the wiring harness and connectors under the passenger seat for damage, corrosion, or loose pins.
Use a scan tool to read live data from the occupant detection system and compare weight readings with known loads.
Perform a zero-point calibration or relearn procedure for the occupant detection system as specified by the manufacturer.
Check for technical service bulletins (TSBs) or software updates related to the occupant detection system for the vehicle make and model.
If sensor readings are inconsistent, replace the occupant classification sensor mat or weight sensor according to service information.
If all else fails, replace the passenger occupant detection system control module and perform initialization.

Common misdiagnosis traps for B0128

A weak or failing battery can cause the occupant detection module to lose its calibration, setting B0128 without any physical fault in the seat.
Aftermarket seat covers, cushions, or heavy objects left on the passenger seat are frequently overlooked causes of false occupant detection faults.
The occupant detection system often requires a zero-point calibration after any seat removal or replacement, and skipping this step will immediately reset the code.
B0128 can be set by a communication fault on the Controller Area Network (CAN) bus between the occupant detection module and the airbag control module, so check network integrity before replacing parts.
On some vehicles, the passenger airbag indicator light bulb or LED failure can trigger a related code, so verify the indicator operation as part of diagnosis.

Can I keep driving with B0128?

You can generally drive the vehicle, but the passenger airbag may be disabled or may not deploy correctly in a crash, so avoid carrying passengers in the front seat until the fault is repaired. Have the system diagnosed promptly to restore full supplemental restraint function.

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.