Airbag control unit with part number BHP1-57K30

What does the airbag control unit BHP1-57K30 do?

The airbag control unit BHP1-57K30 is the device in the restraint system (SRS) of Mazda that evaluates the crash sensors. In a crash, it decides within a few milliseconds which airbags and seatbelt pretensioners are triggered, and it monitors the system continuously. Reported faults appear via the airbag warning light in the instrument cluster.

After an accident, it stores crash data and locks itself.

The sensors provide the basis, but the decision is made by the control unit. That is exactly why it is indispensable for the safety of the occupants.

Why does the control unit BHP1-57K30 fail?

The most common cause is the storage of crash data after an accident, even if no airbag triggered; a normal diagnostic tool cannot erase this data. Other causes include ageing electronic components, cold solder joints, moisture and corrosion on plug connections, and voltage spikes from the vehicle electrical system.

Whether crash data is created does not depend on whether an airbag triggered. That is why it is one of the causes checked first.

The other causes tend to act gradually: electronic components age, solder joints can go cold, and moisture attacks plug connections.

Voltage spikes occur, for example, with a weak battery or when starting with a jump start. Checking the vehicle electrical system is therefore always part of the diagnosis.

How can you tell that the BHP1-57K30 is defective?

Typical signs are an airbag warning light in the instrument cluster that stays on permanently or intermittently, a fault message in the instrument cluster, no connection to the diagnostic tool, and a fault memory that cannot be cleared. In an emergency, the airbags and seatbelt pretensioners may then possibly not trigger.

If the warning light is on, have the system checked promptly. It is the sign you notice fastest.

A diagnostic tool that finds no connection indicates a fault that does not necessarily lie in the control unit. A fault memory that cannot be cleared is likewise one of the typical findings.

Which vehicles is the BHP1-57K30 fitted in?

The control unit BHP1-57K30 is fitted in these vehicles: Mazda Mazda3 BM (2013-2017), BM Facelift (2017-2019), BN (2013-2017) and BN Facelift (2017-2019).

The list comes from our records for this number.

• Mazda Mazda3 BM (2013-2017)
• Mazda Mazda3 BM Facelift (2017-2019)
• Mazda Mazda3 BN (2013-2017)
• Mazda Mazda3 BN Facelift (2017-2019)

Some checks come before you send the unit in. Comparing the part number on the label of the removed unit with this page only confirms that it is the correct unit. Have the fault memory read out beforehand, so that it is clear whether the control unit is defective or a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers BHS2-57-K30A, BRE7-57K30, BRE7-57K30A.

How does the repair of the BHP1-57K30 work?

You begin with the fault memory, attach the log and disconnect the battery before removing the control unit. Then you create the repair order online and send the unit in well packed. Airbag24 checks it on the test bench, repairs defective components, erases stored crash data and carries out a function test before your unit is returned to you.

The order is binding, because the restraint system is affected by the removal. Deviating from it would be safety-relevant.

Processing time at Airbag24 is usually 3–4 working days and refers only to testing, repairing and function-testing there.

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 BHP1-57K30 get to Airbag24?

You either send the unit as a parcel or book a UPS collection for an extra charge. After the repair, UPS brings it back to you.

Pack the unit shockproof and put the printed repair order into the parcel.