B275296 - Passenger sensor mat seat occupancy detection, internal component fault airbag control unit fault

What does error code B275296 mean in the airbag control unit?

Error code B275296 reports a malfunction of the seat occupancy detection at the sensor mat of the passenger seat, more precisely an internal component fault. The airbag control unit stores the fault and switches on the airbag warning light because the mat delivers no valid signal.

The seat occupancy mat on the passenger side is affected. It tells the airbag control unit whether the passenger seat is occupied. If this signal is missing, the control unit cannot control the passenger airbag correctly.

The code B275296 consists of a basic code and the fault type behind it. The fault type says that the component itself reports the fault internally and not just its connection.

How do you recognise error code B275296?

The airbag warning light stays on permanently, and the code B275296 is in the fault memory. This can only be established with a diagnostic tool. If you clear the entry, it returns for as long as the sensor mat sends no valid values.

The fault memory shows it clearly: the code is stored there together with the fault type. You can only see it when a diagnostic tool reads out the memory.

What causes error code B275296?

The sensor mat itself is the obvious suspect, since the code reports an internal component fault. The connector and wiring of the seat occupancy detection or the evaluation in the airbag control unit can also disturb the signal and trigger the entry.

• The sensor mat in the passenger seat is defective internally.
• The connector of the mat has contact problems.
• A wire to the mat is damaged.
• The airbag control unit does not evaluate the mat signal correctly.

Which of these causes applies only becomes clear on inspection. The connector and wiring should therefore be examined as well before the mat is established as the cause.

In which vehicles does error code B275296 occur?

Error code B275296 is known on Mercedes-Benz, for example on the SLK R172 and the A-Class W176. For other vehicles the meaning may differ, and the list makes no claim to completeness.

It always refers to the seat occupancy mat on the passenger side. Whether your vehicle is affected is shown by the fault memory once it has been read out.

How is error code B275296 resolved?

Have the fault memory read out with a diagnostic tool and have the connector and wiring of the seat occupancy detection checked in a specialist workshop. If the sensor mat is defective, Airbag24 offers a simulator for a defective seat occupancy mat.

Work on the airbag system belongs in expert hands. A specialist workshop can determine whether the connector, the wiring or the mat is the cause.

If the cause is not the mat, connector or wiring but the airbag control unit itself, first disconnect the battery, remove the control unit, create a repair order online and send the unit to Airbag24. Checking, repairing and testing usually take 3–4 working days.

The simulator permanently sends the airbag control unit the same signal that an intact mat reports when the seat is occupied.

The simulator is intended exclusively for motorsport use and is not approved for public road traffic (StVO). With the simulator fitted, the passenger airbag deploys in an accident even when the seat is empty. A rear-facing child seat must therefore not be used on the front passenger seat.