Airbag control unit with part number A4519010901

What does the airbag control unit A4519010901 do?

The airbag control unit A4519010901 coordinates the restraint system (SRS) of Smart. It processes the crash sensor data, decides in an accident on airbags and seatbelt pretensioners, and monitors the system during operation. After an accident it stores crash data and locks itself.

The evaluation takes place within milliseconds and allows no delay. The unit therefore checks itself and its connections continuously.

If it detects a fault, this appears via the airbag warning light in the instrument cluster.

Why does the control unit A4519010901 fail?

The most common cause is stored crash data after an accident, even if no airbag has deployed, and an ordinary diagnostic tool cannot erase it. Other causes are ageing electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

Crash data remains in the memory until the repair removes it. An ordinary diagnosis does not access it, which is why the fault persists after an accident.

Ageing components and cold solder joints lead to contact problems. Moisture and corrosion at the plug connections impair the signals, and voltage spikes from a weak battery or a jump start stress the electronics.

How can you tell that the A4519010901 is defective?

A defect shows up as the airbag warning light in the instrument cluster lighting up permanently or intermittently, as an error message, as a diagnostic tool with no connection, and as a fault memory that cannot be cleared. In that case airbags and seatbelt pretensioners may fail to deploy in a crash.

The warning light is the unit's direct display. It points to the defect as soon as it occurs and therefore deserves full attention.

A diagnostic tool that cannot make a connection, and a fault memory that cannot be emptied, additionally point to the control unit.

Which vehicles is the A4519010901 fitted in?

The A4519010901 is fitted in these vehicles: Smart Fortwo C451 (2007-2015).

The list shows the vehicles 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 only confirms that it is the correct unit. Have the fault memory read out beforehand, because only that result 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 A4519010901 work?

Before removal you read out the fault memory and enclose the log. Then disconnect the battery and only then remove the control unit. Next, create a repair order online and send the unit in well packed. Processing at Airbag24 usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components where necessary, erases the stored crash data and carries out a function test. After that the 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 A4519010901 get to Airbag24?

You send the unit in as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 sends it back by UPS.

Put the printed repair order into the parcel and pack the unit shock-proof.