Airbag control unit with part number VA4057K30

What is the function of the Airbag Control Unit VA4057K30?

The Airbag Control Unit VA4057K30, also known as the SAS Unit, is the central control unit for the occupant protection system in the Mazda CX-50. It continuously monitors signals from impact sensors and seat occupancy detectors, deploys airbags and pretensioners in the event of a crash, and stores relevant event and fault data in its internal memory.

The control unit with part number VA4057K30 serves as the brain of the Supplemental Restraint System (SRS). Its primary task is to process data received from various sensors throughout the vehicle, including acceleration sensors for detecting collisions, seat occupancy sensors, and status indicators for each airbag and pretensioner component.

Once sensor readings exceed predefined thresholds, the module sends ignition signals to the corresponding airbags and pretensioners. Simultaneously, all relevant event data—including so‑called crash data—is permanently stored in non-volatile memory.

The module is typically installed in the center tunnel beneath the vehicle’s center console. Due to its safety‑critical role, its multi‑pin connectors are secured with special locking tabs to prevent accidental manipulation or disconnection.

Why does the VA4057K30 control unit fail?

The most common reason for repairing the VA4057K30 is the storage of crash data after an airbag deployment. The module locks itself internally to preserve this data. Other failures manifest through specific diagnostic trouble codes such as B1193, B1A55, or U2107, which indicate internal electronic malfunctions or communication issues.

The primary cause requiring repair of the VA4057K30 is the system‑level lockout following an airbag deployment. The control unit saves crash data in its internal memory and enters a locked state. This condition cannot be reset using standard workshop scanners because the data is marked as permanent.

In addition to storing crash data, internal electronic faults may also occur. These often present as persistent diagnostic trouble codes (DTCs) that cannot be cleared, such as B1A55, B1206, U2107:00‑48, or B1193:00‑8B—indicating malfunctions within the module itself.

In rarer cases, crash data may accumulate in memory even without an actual collision, necessitating repair. Complete refusal to communicate with a diagnostic tool is another clear sign of a defect in the control unit itself.

How do you recognize a fault in the VA4057K30?

A fault in the VA4057K30 control unit primarily manifests as a constantly illuminated or intermittently flashing airbag warning light on the instrument panel. Additional signs include unerasable fault codes in the diagnostic memory or complete inability to communicate with the control unit via a diagnostic tool.

The most obvious symptom of an issue with the airbag control unit is the illuminated SRS warning lamp in the cockpit. This alerts the driver that the occupant protection system is either non‑functional or only partially operational, potentially failing to deploy correctly in the event of a crash.

Diagnostics performed at a workshop often reveal fault codes that persist even after addressing potential external causes. Common examples include B1A55 or B1193.

A more serious symptom occurs when the control unit becomes completely unreachable through the diagnostic interface. The diagnostic tool cannot establish a connection, complicating troubleshooting and usually pointing directly to an internal malfunction within the module.

In which models is the VA4057K30 installed?

The airbag control unit with part number VA4057K30 is specifically used in Mazda vehicles. It is the original equipment manufacturer (OEM) part number for the SAS Unit in the Mazda CX‑50 KJ series, produced starting from the 2022 model year. Compatibility covers all variants within this timeframe.

At Airbag24, we repair the VA4057K30 part number for the following specific vehicle model:

Mazda: CX‑50 (KJ series, from the 2022 model year onward)

According to the manufacturer, this control unit is designed for all variants of the Mazda CX‑50 KJ built between the 2021 and 2025 model years, with serial production beginning in the 2022/2023 model year.

How is the VA4057K30 professionally repaired?

Professional repair at Airbag24 focuses on resetting the internal memory. Upon receipt, the module is thoroughly analyzed, and stored crash data is erased using specialized procedures. A functional test then confirms full operational readiness of the SRS. Repairs come with 2 years' statutory liability for defects.

Before working on the SRS system, the vehicle battery must be disconnected and the manufacturer‑specified waiting period observed to prevent unintended deployment. After proper removal, the control unit is sent to Airbag24.

Here, an initial incoming inspection is performed. The core of the repair involves erasing crash data locked after an accident from the non‑volatile memory. This process requires specialized hardware and software, as simply clearing the fault memory is insufficient.

Following a successful reset, the control unit undergoes a verification test to ensure all functions of the Supplemental Restraint System are operating correctly again. No further coding or programming in the vehicle is required after installation, simplifying the process and saving costs. All repairs at Airbag24 come with 2 years' statutory liability for defects.