Airbag control unit with part number A4518202785

What does the airbag control unit A4518202785 do?

The airbag control unit A4518202785 is the central control unit of the restraint system (SRS) for Smart. It evaluates the signals from the crash sensors, decides in an emergency whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

The decision is made within a fraction of a second. The unit reports faults via the airbag warning light in the instrument cluster.

After an accident, it stores crash data and then locks itself.

Why does the control unit A4518202785 fail?

The most common cause with the A4518202785 is crash data from an accident, which remains stored even if no airbag has deployed and cannot be erased with a normal diagnostic tool. Other causes are:

• aged electronic components
• cold solder joints
• moisture and corrosion at plug connections
• voltage spikes, for example from a weak battery or jump-starting

Airbag24 removes the crash data as part of the repair. The other points concern electronics that age over the years.

Not every fault has the same cause, which is why reading out the fault memory provides clarity.

How can you tell that the A4518202785 is defective?

A fault on the A4518202785 usually shows up as the airbag warning light in the instrument cluster, which lights up permanently or intermittently. A fault message there, a lack of contact with the diagnostic tool and a fault memory that cannot be cleared are also part of it.

Airbags and seatbelt pretensioners may then be unable to deploy in an emergency. The light must therefore be taken seriously.

Keep a close eye on the indicators on the dashboard, because they are the most direct sign of the restraint system.

Which vehicles is the A4518202785 fitted in?

The control unit A4518202785 is fitted in these vehicles: Smart Fortwo C451 (2007-2015).

The following list shows the vehicles assigned to this part number.

• Smart Fortwo C451 (2007-2015)

Compare the part number on the label of the removed unit with this page. This only ensures that it is the correct unit. Have the fault memory read out beforehand, because this result shows whether the control unit is defective or whether a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers A451 820 24 85, A4518201585/001, A4518202285, A4518202485/002, A4519011300Q02.

How does the repair of the A4518202785 work?

First read out the fault memory and enclose the log. Then disconnect the battery and only then remove the control unit A4518202785.

Then create a repair order online and pack the unit well for dispatch. At Airbag24 the unit is checked, defective components are repaired, the crash data is erased and a functional test is carried out.

Processing at Airbag24 usually takes 3–4 working days. Afterwards, your own unit goes back 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 A4518202785 get to Airbag24?

You send the control unit A4518202785 as a parcel, or you book a UPS collection for an extra charge. After the repair, Airbag24 returns it by UPS.

Put the printed repair order in the parcel and pack the unit shock-resistant.