Airbag control unit with part number A4518201485

What does the airbag control unit A4518201485 do?

The airbag control unit A4518201485 is the central control unit of the restraint system (SRS) of Smart. It takes in the signals from the crash sensors, determines within milliseconds in an accident which airbags and seatbelt pretensioners to trigger, and monitors the state of the system during driving. It shows detected faults via the airbag warning light.

To evaluate the data, the unit works with the measurement data from the sensors distributed across the vehicle. It distinguishes events that require a trigger from all other processes.

After an accident, it stores crash data and locks itself. The stored data record the event.

Why does the control unit A4518201485 fail?

Crash data stored in the unit after an accident is the most common cause, even when no airbag was triggered. A normal diagnostic tool does not remove it. Added to this are aged electronic components, cold solder joints, moisture and corrosion on plug connections, and voltage spikes such as those from a weak battery or jump-starting.

The stored crash data sit in the control unit, regardless of whether an airbag fired. The vehicle may appear unremarkable from the outside.

The other causes lie in the electronics and their connections. A plug contact with moisture or corrosion can cause a malfunction that looks very much like a defective unit.

How can you tell that the A4518201485 is defective?

The airbag warning light in the instrument cluster lights up constantly or intermittently, there is an error message, a missing connection to the diagnostic tool, and a fault memory that cannot be cleared. In a crash, the airbags and seatbelt pretensioners may then fail to trigger on the A4518201485.

The lit warning light is therefore a clear reason to have the system checked.

Which vehicles is the A4518201485 fitted in?

The A4518201485 is fitted in these vehicles: Smart Fortwo C451 (2007-2015).

The list shows the models assigned to this part number.

• Smart Fortwo C451 (2007-2015)

Before you place the order, compare the number on the label of the unit with this page, so you know you have the right unit. Also have the fault memory read out. It shows whether the control unit is defective or whether a plug 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 A4518201485 work?

Have the fault memory read out and keep the log. Then disconnect the battery and remove the A4518201485. Online, you create the repair order and send the unit in, well packed. At Airbag24, checking, repairing and testing usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components and erases the crash data. A function test follows, after which 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 A4518201485 get to Airbag24?

You send the unit to Airbag24 as a parcel, or you book a UPS collection for an extra charge. After the repair, UPS brings the control unit A4518201485 back. Place the printed repair order in the carton.

A sturdy carton with padding protects the unit from knocks.