Airbag control unit with part number UR56-57-K30B

What is the function of the airbag control unit UR56-57-K30B?

The airbag control unit with part number UR56-57-K30B is the central control unit (SRS Control Unit) for the passive safety system in Mazda and Ford vehicles. It processes data from acceleration and crash sensors and determines, within milliseconds, whether and when airbags and seatbelt pretensioners should be deployed.

As the brain of the restraint system, this component continuously monitors all connected sensors, airbag modules, and seatbelt pretensioners. In the event of a crash, relevant incident data—known as crash data—is stored directly in the control unit’s memory. This function is crucial for post-crash analysis.

The UR56-57-K30B is an original Mazda OEM part number. Due to platform collaborations between manufacturers, however, this specific control unit is used not only in Mazda models but also in mechanically identical vehicles such as the Ford Ranger.

Why does the UR56-57-K30B control unit fail?

The most common cause of failure for the UR56-57-K30B control unit is the storage of crash data after a traffic accident. Other causes include electrical issues such as faulty wiring, loose connectors, or voltage surges, which can lead to internal hardware defects and specific error codes like B1000 (control unit defective).

Following a collision, the control unit deliberately locks itself by securely storing crash data. This is a safety measure, not a software bug. The device thus signals that the entire restraint system must be inspected before it can be put back into operation.

Electrical malfunctions are another frequent source of failure. Broken wires, corrosion at connector contacts, or voltage fluctuations in the vehicle’s electrical system can damage sensitive electronic components inside the control unit. These issues often manifest as internal errors or communication problems.

In workshop diagnostics, specific error codes are read out, indicating a defect. Typical for the UR56-57-K30B are errors such as B1000, B1015, B107E, B1139, or even the internal DTC 93D7 error code, which may point to surge-related damage. The related variant UR5657K30B also refers to the same component.

How do you recognize a defect in the UR56-57-K30B?

A defect in the UR56-57-K30B airbag control unit typically manifests as a permanently illuminated airbag warning light (SRS lamp) on the instrument cluster. Another clear symptom is the loss of communication, where diagnostic tools can no longer access the control unit.

The primary indicator is the red SRS warning light. It fails to turn off after starting the vehicle, signaling that the passive safety system is not operational and would not deploy in the event of an accident.

An additional serious symptom is complete communication failure. When the workshop attempts to read the fault memory, the diagnostic tool reports that no connection can be established with the airbag control unit. This points to a severe internal defect.

Before total failure, error codes may also be stored in memory, indicating issues such as excessive resistance in the airbag circuit or CAN bus errors. These too are serious indicators of an impending problem with the control unit.

In which models is the UR56-57-K30B installed?

The UR56-57-K30B control unit is primarily installed in various generations of the Mazda BT-50, ranging from the J97M series (2006–2012) through the UP (2011–2020) to the TF (from 2020 onward). Due to technical similarities, it is also used in platform‑related Ford Ranger models.

At Airbag24, we repair the UR56-57-K30B control unit for the following vehicles:

Mazda: BT-50 J97M (2006–2008), BT-50 J97M Facelift (2008–2012), BT-50 UP (2011–2020), BT-50 TF (2020–2024)

Ford: Ranger (related models, e.g., model year 2011)

How is the UR56-57-K30B repaired?

Professional repair of the UR56-57-K30B follows a standardized process. Upon submission to Airbag24, an initial thorough diagnosis is performed. Next, stored crash data is erased and the unit is reprogrammed. Internal defects are fixed, and the repair concludes with a functional test.

After sending the unit to Airbag24, systematic refurbishment begins. The first step always involves reading the fault memory using specialized equipment to pinpoint the exact cause of the issue—whether it’s stored crash data or an internal hardware defect.

The core of the repair lies in reprogramming the control unit to lift the crash‑induced lock and erase all error codes. If physical damage caused by voltage surges or other electrical faults is present, the defective components on the circuit board are professionally replaced.

After repair, each control unit undergoes a comprehensive functional test. This ensures it performs like new and maintains full communication with the vehicle. We offer 2 years' statutory liability for defects on all repairs.