Airbag control unit with part number A 001 820 08 26 (03)

What does the airbag control unit A 001 820 08 26 (03) do?

The airbag control unit A 001 820 08 26 (03) is the central control unit of the restraint system (SRS) for Mercedes-Benz. It evaluates the signals from the crash sensors, decides within milliseconds in an accident whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

If the unit detects a fault during operation, it reports it via the airbag warning light in the instrument cluster. In this way you find out that the restraint system is no longer fully ready.

After an accident, the control unit stores crash data and then locks itself. All sensor signals come together in this unit, so the function of the entire restraint system depends on its work.

Why does the control unit A 001 820 08 26 (03) fail?

The most common cause is crash data stored after an accident, even if no airbag has triggered. Other possible causes are aged electronic components, cold solder joints, moisture and corrosion on plug connections, and voltage spikes, for example from a weak battery or jump-starting.

Stored crash data cannot be erased with a normal diagnostic tool. Airbag24 removes it during the repair.

The remaining causes affect the electronics themselves or their connections: solder joints can go cold, moisture and corrosion disturb the signal transmission at the plugs, and voltage spikes put stress on the components in the unit. Which cause applies to your control unit is only shown by a diagnosis.

How can you tell that the A 001 820 08 26 (03) is defective?

A defect shows up as the airbag warning light in the instrument cluster staying on permanently or lighting up intermittently. A fault message in the instrument cluster, or a diagnostic tool that cannot connect to the control unit, also points to it.

• The airbag warning light stays on permanently or lights up intermittently.
• A fault message about the restraint system appears in the instrument cluster.
• The diagnostic tool does not establish a connection to the control unit.
• The fault memory cannot be cleared.

With such a finding, airbags and seatbelt pretensioners may fail to deploy in an emergency. The warning light makes precisely these faults visible, so take it seriously and have the cause investigated.

Which vehicles is the A 001 820 08 26 (03) fitted in?

The control unit A 001 820 08 26 (03) is fitted in these vehicles: Mercedes-Benz A-Class W168 (1997-2004).

These vehicles are stored for this part number:

• Mercedes-Benz A-Class W168 (1997-2004)

Compare the part number on the label of the removed unit with this page; this only ensures that you have the right unit in front of you. Also have the fault memory read out beforehand, because only its result shows whether the control unit is defective or whether a plug or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 0018203126(09), 0285001467, 285001222, A 001 820 08 26 (08), A0018203126, A0028203826.

How does the repair of the A 001 820 08 26 (03) work?

First you read out the fault memory and enclose the log, then you disconnect the battery and only then remove the control unit. Next you create a repair order online and send in the well-packed unit.

Airbag24 checks the unit on the test bench, replaces defective components, erases the stored crash data and carries out a function test. Processing at Airbag24 usually takes 3–4 working days.

Your own unit is then returned to you. Our repairs come with 2 years' statutory liability for defects. 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.

How does the control unit A 001 820 08 26 (03) get to Airbag24?

You send the control unit as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns it to you by UPS.

Put the printed repair order into the parcel and pack the unit so that it is protected against shocks.