B1561 - Crash data stored (deployment threshold exceeded) airbag control unit fault

What does error code B1561 mean in the airbag control unit?

On Mercedes-Benz vehicles, error code B1561 reports that crash data is stored in the control unit because the trigger threshold was exceeded in an accident. The control unit itself stores this fault in the fault memory and switches on the airbag warning light, which shows the fault to the driver.

The code relates to the crash data stored in the control unit itself, and therefore to the accident in which the trigger threshold was exceeded.

In an emergency, the control unit triggers the airbags and seatbelt pretensioners, and it is this very control unit that has stored the crash data.

How do you recognise error code B1561?

You recognise error code B1561 by the airbag warning light staying on permanently and the code being stored in the fault memory of the airbag control unit. The entry cannot be permanently deleted, and it is read out with a suitable diagnostic tool connected to the vehicle.

If the airbag warning light stays on permanently, this points to a stored fault in the control unit. Only the readout with a diagnostic tool shows whether you have error code B1561. Until then, it cannot be said whether an accident is behind it.

What causes error code B1561?

For this code, the cause lies in an accident in which the trigger threshold was exceeded and the crash data was stored in the control unit. In addition, for internal faults in the control unit, the possible triggers are ageing electronic components, soldered joints, moisture or corrosion, and voltage spikes.

• Crash data from an accident
• Ageing electronic components in the control unit
• Soldered joints, moisture or corrosion in the unit
• Voltage spikes caused by a weak battery or by jump-starting

Whether an accident caused the crash data or an internal fault is present is only shown by examining the control unit.

In which vehicles does error code B1561 occur?

Error code B1561 is known on Mercedes-Benz vehicles, for example the A-Class, CLA-Class, CLE-Class, G-Class, GLC-Class, AMG GT and EQT. The meaning may differ on other vehicles, and the list is not complete.

Whether the code is present on your vehicle is only shown by the fault memory once it has been read out. Stating the make and model alone proves nothing in this respect. What counts is what the diagnostic tool actually finds in the control unit.

How is error code B1561 resolved?

Because the cause lies in the control unit itself, error code B1561 is resolved by removing the unit and repairing it at Airbag24 in Berlin. Beforehand, you have the fault memory read out with a diagnostic tool, and the battery is disconnected before the control unit is removed.

To do this, you create a repair order online and send the removed control unit to Airbag24. Inspection, repair and testing usually take 3–4 working days.

The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

Work on the airbag system should be left to qualified specialists. Removing the control unit also requires the battery to be disconnected beforehand. Safety comes first.