Airbag control unit with part number BR5S-57K30C

What does the airbag control unit BR5S-57K30C do?

The airbag control unit BR5S-57K30C is the central control unit of the restraint system (SRS) for Mazda. It evaluates the signals from the crash sensors and, in the event of an accident, decides within split seconds which airbags and seatbelt pretensioners are triggered. It reports faults via the airbag warning light in the instrument cluster.

The unit monitors the system continuously. After an accident it stores crash data and locks itself. The housing also bears the manufacturer number Bosch 0285001960.

Why does the control unit BR5S-57K30C fail?

Stored crash data is the most common cause in the control unit BR5S-57K30C: it comes from an accident, even if no airbag was deployed, and it cannot be erased with a normal diagnostic tool. Other possible causes include aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

The crash data is created in the unit after the accident. Airbag24 erases it during the repair, so you do not need to do anything.

Aged components and cold solder joints can cause contact problems over time. Voltage spikes, for example from a weak battery or a jump start, put additional strain on the electronics.

How can you tell that the BR5S-57K30C is defective?

A defect in the BR5S-57K30C shows up as the airbag warning light in the instrument cluster, which lights up permanently or intermittently.

• Fault message in the instrument cluster.
• The diagnostic tool cannot connect to the control unit.
• The fault memory cannot be erased.

In an emergency, airbags and seatbelt pretensioners may then fail to trigger. A lit warning light should therefore be taken seriously.

Which vehicles is the BR5S-57K30C fitted in?

The BR5S-57K30C is fitted in these vehicles: Mazda Mazda3 BK Facelift (2006-2009) and BK (2003-2006).

The vehicles at a glance:

• Mazda Mazda3 BK Facelift (2006-2009)
• Mazda Mazda3 BK (2003-2006)

Compare the part number on the label of the removed unit with this page; this only confirms that it is the correct unit. Also have the fault memory read out beforehand, because only this result shows whether the control unit is defective or whether a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 131000-1022, 285001453, 285001553, 285001554, BP4K-57K30, BP4K-57K30B.

How does the repair of the BR5S-57K30C work?

First have the fault memory of the control unit BR5S-57K30C read out and include the log in the package. Then disconnect the battery and only then remove the control unit. Next, create a repair order online and send in the well-packed unit.

Airbag24 checks the unit on the test bench, replaces defective components and carries out a function test. Airbag24 also erases stored crash data. Processing usually takes 3–4 working days.

The unit is then 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 BR5S-57K30C get to Airbag24?

You send the control unit BR5S-57K30C as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns it to you by UPS.

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