Airbag control unit with part number 28556-4CH0A

What does the airbag control unit 28556-4CH0A do?

The airbag control unit 28556-4CH0A is the central control unit of the restraint system (SRS) for Nissan. It evaluates the signals from the crash sensors and decides in a crash, within milliseconds, which airbags and seatbelt pretensioners are triggered.

While the vehicle is in use, the unit monitors the entire restraint system without a break. If it detects a fault, it reports this via the airbag warning light in the instrument cluster. In everyday life this part of the car stays out of sight, yet its reliability decides in an emergency whether the protective system works.

After an accident the control unit stores crash data and then locks itself. Only the repair lifts this lock.

Why does the control unit 28556-4CH0A fail?

The most common cause with the 28556-4CH0A is crash data stored after an accident, even if no airbag was triggered. Further triggers are ageing components, moisture, corrosion and voltage spikes.

Crash data remains stored until it is removed. A standard diagnostic tool cannot do this. Airbag24 erases it during the repair.

Besides the crash data, the following further causes are possible:

• ageing electronic components
• cold solder joints
• moisture and corrosion at plug connectors
• voltage spikes, for example from a weak battery or a jump start

How can you tell that the 28556-4CH0A is defective?

A defect in the 28556-4CH0A shows up on the airbag warning light in the instrument cluster, which stays on permanently or intermittently, and in a fault message there. In addition, the diagnostic tool has no connection to the control unit, and a fault memory cannot be cleared.

These signs are not trivial. In an emergency, airbags and seatbelt pretensioners may fail to trigger even though the vehicle drives as usual. It is therefore worth having the cause checked promptly.

The warning light shows the fault directly. A glance at the instrument cluster is enough to see that something is wrong, and a diagnosis then establishes the cause.

Which vehicles is the 28556-4CH0A fitted in?

The control unit 28556-4CH0A is fitted in these vehicles: Nissan X-Trail T32 (2014-2017) and T32 Facelift (2017-2022). The assignment applies only to this exact part number.

The following vehicles are recorded for this part number:

• Nissan X-Trail T32 (2014-2017)
• Nissan X-Trail T32 Facelift (2017-2022)

Compare the part number on the label of the removed unit with this page. This only ensures that you have the right unit in front of you. Have the fault memory read out before removal, because only then can you see whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 1520831000, 152083100B, 1520831U00, 1520831U01, 1520831U0A, 98820JH43A.

How does the repair of the 28556-4CH0A work?

First read out the fault memory and attach the log. Then disconnect the battery, and only after that remove the 28556-4CH0A. Create the repair order online and send in the well-packed unit.

Airbag24 checks the unit on the test bench, replaces defective components, erases the stored crash data and carries out a function test. Afterwards the unit, now repaired, goes back to you.

Processing at Airbag24 usually takes 3–4 working days. This period refers exclusively to checking, repairing and testing at Airbag24. 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 28556-4CH0A get to Airbag24?

You send the 28556-4CH0A as a parcel or book a UPS collection for an extra charge. After the repair Airbag24 sends it back via UPS.

Enclose the printed repair order in the parcel and pack the control unit shock-resistant.