Airbag control unit with part number 402792B2

What does the airbag control unit 402792B2 do?

The airbag control unit 402792B2 controls the restraint system (SRS) for Renault. It evaluates the crash sensors and, in an impact, decides within milliseconds whether airbags and seatbelt pretensioners are triggered, and it monitors the system without interruption. It indicates faults via the airbag warning light.

The evaluation takes place in the background while the vehicle is driving. The signals from several sensors are compared with one another before a decision is made.

After an accident, the unit stores crash data and locks itself.

Why does the control unit 402792B2 fail?

Most often the cause is crash data stored after an accident, even if no airbag was triggered; a normal diagnostic tool cannot erase it. Other possible causes are aged electronics, cold solder joints, moisture and corrosion on plug connectors, and voltage spikes, for example from a weak battery or a jump start.

If no airbag was triggered, that does not mean that no data is stored in the memory. The memory records the event regardless of whether an airbag actually triggers.

The other causes mainly concern the electronics and their connections. Over time, components can deteriorate, and moisture attacks plug connectors. Voltage spikes additionally act on the circuits.

How can you tell that the 402792B2 is defective?

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

The warning light is the display by which the control unit reports a defect. It does not only become active in an accident but with every detected fault in the system.

If you see the light permanently or only intermittently, have the vehicle checked promptly. Only the read-out shows the cause.

Which vehicles is the 402792B2 fitted in?

The control unit 402792B2 is fitted in these vehicles: Renault Twingo II (2007-2014). What is decisive is the assignment of the part number to your own car.

Below you see the vehicles for which this number is recorded.

• Renault Twingo II (2007-2014)

Before you remove the unit, compare the part number on the label with this page. That only confirms that it is the right unit. The cause is clarified only by the fault memory, which you should have read out beforehand: it shows whether the control unit is defective or whether a plug or cable is causing the problem.

For the same vehicles, we also repair control units with the part numbers 402787B3, 8200 491 652, 8200054938, 8200111668, 8200491655, 8200896811.

How does the repair of the 402792B2 work?

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

At Airbag24, the unit is first checked on the test bench. Airbag24 then replaces defective components, erases stored crash data and carries out a functional test.

Afterwards your own unit is sent 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 402792B2 get to Airbag24?

Either you send the unit as a parcel, or you book a UPS collection for an extra charge. After the repair, Airbag24 sends the unit back to you by UPS.

The printed repair order belongs in the package, and in addition the control unit needs a shock-resistant casing.