B106C - Communication fault with passenger seat occupancy and child seat detection airbag control unit fault

What does error code B106C mean in the airbag control unit?

Error code B106C reports a communication fault between the airbag control unit and the seat occupancy and child seat detection of the passenger seat. A wiring fault can also be behind it. The control unit stores the fault and switches on the airbag warning light.

The detection on the passenger side tells the airbag control unit whether the seat is occupied and whether a child seat is on it. If the connection breaks off or no response arrives, the control unit cannot control the passenger airbag correctly.

How do you recognise error code B106C?

The airbag warning light stays on permanently, and the code B106C is in the fault memory. It is read out with a diagnostic tool. After clearing, the entry returns for as long as the connection to the seat occupancy detection remains disturbed.

• The airbag warning light stays on permanently.
• The diagnostic tool shows the communication fault in the fault memory.
• The light does not go out even when the passenger seat is empty.

What causes error code B106C?

The cause is an interrupted or disturbed connection to the seat occupancy and child seat detection. This can lie in the detection itself, in its connector or in the wiring. The airbag control unit may also fail to receive the response correctly.

• The seat occupancy and child seat detection in the passenger seat does not respond.
• The connector has a loose contact or corrosion.
• A wire is broken or damaged.
• The reception in the airbag control unit does not work properly.

A check of the connection in a specialist workshop shows which part is affected. The connector and wiring are checked just as much as the seat occupancy and child seat detection itself.

In which vehicles does error code B106C occur?

Error code B106C is known on Mercedes-Benz, for example on the C-Class W202 and W203 and on the CLK C208. For other vehicles the meaning may differ, and the list is not complete.

Other Mercedes-Benz models with seat occupancy detection may also show the entry. The fault memory, once read out, clarifies this. For vehicles not listed here, the same code may mean something else.

How is error code B106C 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 itself is defective, Airbag24 offers a simulator for a defective seat occupancy mat.

Work on the airbag system belongs in expert hands. The specialist workshop checks the wiring and the connector and determines whether the connection 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.