Airbag control unit with part number BEPN-57K30D

What does the airbag control unit BEPN-57K30D do?

The airbag control unit BEPN-57K30D coordinates the restraint system (SRS) of Mazda. It evaluates the crash sensors, determines in the event of an accident which airbags and seatbelt pretensioners are triggered, and monitors the entire system during operation.

The unit reports faults via the airbag warning light in the instrument cluster. This makes a malfunction visible to the driver.

After an accident the unit stores crash data and locks itself. The following sections show what this means for a repair.

Why does the control unit BEPN-57K30D fail?

Most often the cause lies in crash data stored after an accident, even if no airbag was triggered. Other causes include aged components, cold solder joints, moisture and corrosion, and voltage spikes.

Crash data cannot be removed with a standard diagnostic tool. For this reason it must be examined separately during fault finding.

The other causes affect the electronics and their connections. A weak battery or a jump start can cause voltage spikes that stress the unit.

How can you tell that the BEPN-57K30D is defective?

The airbag warning light in the instrument cluster stays on permanently or intermittently, and an error message appears in the instrument cluster. The diagnostic tool cannot establish a connection to the control unit, and the fault memory cannot be cleared. In a crash, the airbags and seatbelt pretensioners may then fail to deploy.

The warning light is the first sign you will notice in everyday use. It indicates a fault.

If the light stays on after the ignition is switched on, reading out the fault memory is worthwhile; the report shows the stored messages.

Which vehicles is the BEPN-57K30D fitted in?

The control unit BEPN-57K30D is fitted in these vehicles: Mazda Mazda3 BP (from 2019).

These vehicles are known to us:

• Mazda Mazda3 BP (from 2019)

You can compare the part number on the label of the removed unit with this page yourself. It only shows that you have the correct unit. Have the fault memory read out beforehand. Only this report clarifies whether the control unit itself is defective or whether a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers BCKA-57-K30F, BCKA-57-K30G.

How does the repair of the BEPN-57K30D work?

The process starts with you: read out the fault memory, disconnect the battery, remove the control unit, create a repair order online and send in the unit. At Airbag24 processing usually takes 3–4 working days, during which the unit is checked, repaired and tested.

The order is fixed for safety reasons. Airbag24 replaces defective components, deletes stored crash data and carries out a function test; afterwards your unit is returned 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 BEPN-57K30D get to Airbag24?

You send the control unit as a parcel, or you book a UPS collection for an extra charge. The return after the repair is also made via UPS.

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