Mercedes Seat Occupancy Sensor Fault – Front Passenger
System: Safety System / Airbag System Component: Seat Occupancy Sensor Mat (Passenger Seat)
Typical Symptoms
• Airbag warning light illuminated
• Message relating to passenger airbag or restraint system
• Passenger airbag may be disabled
• Fault stored in safety system
Fault Codes
• B275296 – Seat occupancy sensor mat front passenger malfunction (internal fault)
• B1C1F81 – Seat occupancy recognition front passenger malfunction (incorrect data received)
• B275200 – Seat occupancy sensor front passenger malfunction
Possible Cause
• Faulty seat occupancy sensor mat
• Internal sensor failure
• Incorrect or implausible signal
• Wiring or connector issue
Component Location
The seat occupancy sensor mat was removed from the seat and positioned on top for illustration purposes .
Diagnostic Insight
The seat occupancy sensor determines whether a passenger is present and allows the airbag system to operate correctly.
If the sensor fails, the system may:
• disable the passenger airbag
• store multiple fault codes
• display airbag warning messages
Technicians usually check:
• sensor data using diagnostic equipment
• wiring and connector condition
• seat occupancy readings
In this case, testing confirmed the seat occupancy sensor mat was faulty, and replacement was required.
It is important to confirm the root cause before replacing components.
See Mercedes Fault Diagnosis Guide
Important Note
The seat occupancy sensor mat is integrated into the seat and may require seat removal and component replacement.
Incorrect repair may affect airbag system operation.
⚠ Professional Diagnostic Recommended
Airbag and safety system faults require specialist diagnostic equipment. The vehicle should be inspected by a Mercedes-Benz dealer or qualified Mercedes specialist.
