Airbag control unit with part number A4519012301

What does the airbag control unit A4519012301 do?

The airbag control unit A4519012301 controls the restraint system (SRS) in the Smart. It evaluates the signals from the crash sensors and determines in a crash, within milliseconds, which airbags and seatbelt pretensioners are triggered.

In normal operation, it monitors all connected components. If it detects a fault, it reports it via the airbag warning light.

After an accident, it stores crash data and locks itself. This lock can only be lifted by the repair.

Why does the control unit A4519012301 fail?

The most common cause is crash data from an earlier accident, even if no airbag has deployed. A normal diagnostic tool cannot erase it. Other causes are aged electronic components, cold solder joints, moisture and corrosion on plug connections, and voltage spikes.

The crash data remains in the memory until it is specifically removed. Airbag24 removes it as part of the repair.

Aged components and cold solder joints are typical weak points. Moisture and corrosion attack the plug connections. A weak battery or a jump start can generate voltage spikes that damage the unit.

How can you tell that the A4519012301 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently. In addition, the instrument cluster displays an error message, the diagnostic tool finds no connection to the control unit, and the fault memory cannot be cleared. Then airbags and seatbelt pretensioners may not be triggered in an emergency.

Otherwise, you can recognise the defect by these signs:

• The warning light flashes or stays on constantly
• An airbag message appears in the display
• The diagnostic tool breaks off the connection
• Stored faults return after being cleared

Which vehicles is the A4519012301 fitted in?

The control unit A4519012301 is fitted in these vehicles: Smart Fortwo C451 (2007-2015). The information refers to the make Smart.

The list here shows the vehicles that are stored for this part number.

• Smart Fortwo C451 (2007-2015)

Compare the part number on the label of the removed unit with this page. This way you can see that you have the right unit in front of you. Whether the control unit is defective or a plug or cable is the cause is shown only by the fault memory, which you have read out beforehand.

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 A4519012301 work?

First have the fault memory read out and enclose the log. Then disconnect the battery and remove the control unit. Afterwards, create a repair order online and send the well-packed unit in.

Airbag24 checks the unit on the test bench, rectifies the faults on the affected components, erases the stored crash data and carries out a function test. The processing at Airbag24 usually takes 3–4 working days.

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 A4519012301 get to Airbag24?

You send the 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. Pack the unit shock-proof.