Airbag control unit with part number 28556BC400

What is the function of the airbag control unit 28556BC400?

The airbag control unit with part number 28556BC400 is the central control module for the occupant protection system in the Nissan Micra K12. It processes data from acceleration sensors to precisely deploy the airbags and seatbelt pretensioners at the right moment in the event of a collision, thereby ensuring the safety of vehicle occupants.

As the brain of the passive safety system (SRS – Supplemental Restraint System), this control unit continuously monitors and interprets signals from crash sensors distributed throughout the vehicle. When an impact exceeds predefined thresholds, the unit sends critical ignition pulses to the respective airbag modules and seatbelt pretensioners.

The proper functioning of this component is vital for survival, as a malfunction could result in the restraint systems failing to activate or activating incorrectly during a real-world accident. It is specifically designed for the vehicle architecture of the Nissan Micra K12 generation.

Why does the control unit 28556BC400 fail?

Defects in the 28556BC400 control unit often manifest as a lit SRS warning light. The most common cause is the storage of crash data after an accident, which can lock the unit. Internal hardware defects in individual electronic components can also lead to failure, disabling the airbag functionality.

A major reason for necessary repairs is the permanent storage of so‑called crash data in the control unit’s internal memory. After an accident—even minor collisions—the unit locks itself for safety reasons and must be professionally reset.

In addition, hardware faults may occur directly on the circuit board. Often, only specific components fail. Specialized repair of such parts offers an economical and sustainable alternative to the costly replacement of the entire control unit.

How do you recognize a defect in the 28556BC400?

The primary symptom of a faulty airbag control unit 28556BC400 is an activated SRS warning light on the instrument panel, either blinking or steadily illuminated. This indicates a fault in the restraint system. Consequently, airbags might not deploy in the event of a crash, posing a significant safety risk.

A permanently lit or blinking SRS light after starting the engine is the clearest sign. The system performs a self‑test upon each start; if the test fails, the driver is alerted by the warning light.

Especially after an accident, a lit airbag light clearly indicates that crash data has been stored in the control unit. Even if no external damage is visible and the airbags have not deployed, the control unit may still be internally locked.

In such cases, immediate inspection at a workshop is strongly recommended, as the airbags may be deactivated. Passenger safety is no longer fully guaranteed.

In which vehicles is the 28556BC400 installed?

The airbag control unit with part number 28556BC400 is specifically designed for Nissan Micra models. At Airbag24, this component is repaired for the third generation (K12), covering both the original version and the facelift model. This ensures a precise fit for this vehicle series.

Based on 20 years of experience and over 20,000 repairs performed, Airbag24 has developed deep expertise in servicing this particular control unit. Repairs are offered for the following Nissan models:

Nissan Micra K12 (2003–2005)

Nissan Micra K12 Facelift (2005–2010)

How does the repair process work at Airbag24?

At Airbag24, repairing the 28556BC400 control unit follows a systematic procedure. Upon receipt, the unit is analyzed using state-of-the-art diagnostic equipment to pinpoint the exact source of the fault. Experienced mechatronics technicians then resolve the issue precisely—whether by erasing crash data or replacing defective components.

After the control unit arrives at Airbag24, it undergoes a thorough diagnosis. Various analyses help identify the root cause of the problem, ensuring targeted and efficient restoration.

Subsequently, highly experienced mechatronics technicians carry out the actual repair, employing specialized techniques tailored to the specific weaknesses of this type of control unit. Following successful repair, the unit undergoes a final functional test.

The repair is a plug-and-play solution, meaning the restored control unit can be reinstalled in the vehicle without additional coding or programming. Each repair comes with 2 years' statutory liability for defects.