Airbag control unit with part number 28556-4CM0A

What does the airbag control unit 28556-4CM0A do?

As the restraint system (SRS) control unit of Nissan, the airbag control unit 28556-4CM0A coordinates the safety systems in the interior. In a collision it processes the readings from the crash sensors and decides within milliseconds which airbags and seatbelt pretensioners to fire.

While driving, the unit continuously checks whether all connected components are working. If it detects a fault, it shows this via the airbag warning light.

If the system has been triggered by an accident, the control unit stores crash data and then locks itself. The crash data is therefore part of the unit's function and is not a by-product.

Why does the control unit 28556-4CM0A fail?

Crash data from an earlier accident is the most common cause, even if no airbag was deployed in control unit 28556-4CM0A. A normal diagnostic tool cannot erase it; Airbag24 removes it during the repair. Other causes include aged electronic components, cold solder joints, moisture and corrosion on connectors, and voltage spikes.

Stored data can disrupt operation even when the components themselves are fine. For that reason, it is worth not jumping to the conclusion that a single component is at fault.

The remaining causes mainly affect connections and the power supply. Solder joints weaken over time, connectors lose reliability in damp conditions, and voltage spikes occur, for example, when a vehicle is jump-started.

How can you tell that the 28556-4CM0A is defective?

The airbag warning light in the instrument cluster stays on permanently or intermittently, indicating a defect in control unit 28556-4CM0A. A fault message appears alongside it, the diagnostic tool cannot connect, and the fault memory cannot be cleared; in this case, airbags and seatbelt pretensioners may not deploy in an emergency.

The light is a warning signal, not a cosmetic issue, even if the vehicle otherwise drives normally.

If the warning light comes on, do not wait it out. Have the fault memory read out and keep the log.

Which vehicles is the 28556-4CM0A fitted in?

Control unit 28556-4CM0A is fitted in these models: Nissan X-Trail T32 (2014-2017) and T32 Facelift (2017-2022). This information is based on the assignment of this part number.

Here follows the list of vehicles we have assigned to this unit.

• 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 confirms that it is the correct unit. Having the fault memory read out beforehand, on the other hand, 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 1520831000, 152083100B, 1520831U00, 1520831U01, 1520831U0A, 98820JH43A.

How does the repair of the 28556-4CM0A work?

Have the fault memory read out and attach the log, then disconnect the battery and only then remove control unit 28556-4CM0A. Next, create a repair order online and send in the well-packed unit. Processing at Airbag24 usually takes 3–4 working days.

Airbag24 checks the submitted unit on the test bench, repairs defective components, erases the stored crash data and carries out a function test. Your own unit is then sent back 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 28556-4CM0A get to Airbag24?

You send control unit 28556-4CM0A to us as a parcel, or book a UPS collection for an extra charge. After the repair, Airbag24 returns it to you by UPS.

The printed repair order goes in the parcel; the unit itself is packed shock-proof.