B106F: Passenger Occupancy Sensor Defective

Hardware fault

What B106F means

This sensor lives in the passenger seat cushion and reports what is in the seat so the control unit can enable, suppress, or stage the passenger airbag correctly. It runs self checks and reports status. B106F is the code stored when those checks fail or when the reported values are ones a functioning sensor would never produce.

Occupancy sensors wear out in predictable ways. The sensing element is a mat or a set of elements under the upholstery, and it flexes every time somebody sits down. Years of that, plus spilled drinks, plus people dropping into the seat hard, eventually break an element or shift its calibration far enough that the sensor stops trusting itself.

Common causes

• A failed sensing element inside the passenger seat cushion mat
• Liquid spilled into the seat that reached the sensor electronics
• Repeated heavy loading of the passenger seat, including cargo placed on it
• Aftermarket seat covers or heating pads installed over the sensor mat
• Damage from seat removal or upholstery work
• Long term aging that pushed the sensor calibration out of its usable range

Crash data or hardware fault?

The code names a defective part, which puts it in the hardware family rather than with live circuit readings. The control unit repeats its check at every power up, and the verdict stands until a working sensor is installed. Crash data behaves on another track entirely: it is a permanent deployment record cleared only by a module reset.

Does our reset clear it?

Clearing memory does not repair a sensor that has failed its own diagnostics. Replace the occupancy sensor, run any calibration the model requires, and confirm the system reports occupancy correctly. Our mail in reset applies to Mercedes restraint control units holding crash data or locked internal faults after a deployment.

Which makes throw it

Our lookup carries B106F under Mercedes-Benz, tied to the B48 occupancy and child seat recognition sensor. Since that system varies across their model range, verify which generation of hardware the car carries before sourcing parts or planning a calibration.

What to do next

Confirm the sensor has clean power and ground before replacing anything, because a supply problem can make a good sensor report as failed. Check for spill damage under the seat cushion and for any aftermarket cover or heater sitting on the mat. If the sensor is confirmed bad, the seat cushion sensor assembly is the repair, and we can help match the genuine OEM part and reset the control unit if it also holds crash data. Related codes: B106C, B1071, B1400.