Airbag control unit with part number 28556 ZB201

What does the airbag control unit 28556 ZB201 do?

The airbag control unit 28556 ZB201 is the central control unit of the restraint system (SRS) in Nissan. It checks the signals from the crash sensors, decides in an accident within milliseconds whether airbags and seatbelt pretensioners are triggered, and monitors the system permanently.

If the unit detects a fault, it records it and shows it via the airbag warning light in the instrument cluster. This keeps the system in view, even when nothing unusual happens in everyday use.

After an accident the unit stores crash data and locks itself.

Why does the control unit 28556 ZB201 fail?

Most often the cause is crash data stored after an accident, even if no airbag has deployed; a normal diagnostic tool cannot reach it. Other triggers are aged components, moisture and corrosion at plug connections, and voltage spikes.

Crash data cannot be removed with common tools. It remains stored in the unit until Airbag24 erases it during the repair.

The other causes come down to wear inside the unit. Cold solder joints and voltage spikes, for example from a weak battery, can also play a role.

How can you tell that the 28556 ZB201 is defective?

A defect in the 28556 ZB201 shows up as the airbag warning light, which lights up permanently or intermittently. Then airbags and seatbelt pretensioners may not deploy in an emergency.

The signs in detail:

• Airbag warning light in the instrument cluster lights up permanently or intermittently
• Fault message in the instrument cluster
• The diagnostic tool finds no connection to the control unit
• The fault memory cannot be cleared

Each of these signs is a reason to have the system checked. The warning light being off right now does not mean that everything is in order.

Which vehicles is the 28556 ZB201 fitted in?

The airbag control unit 28556 ZB201 is fitted in these vehicles: Nissan Altima L31 Facelift (2005-2006).

The vehicles in list form:

• Nissan Altima L31 Facelift (2005-2006)

Before you remove the unit, compare the part number on the label with this page. This makes sure you have the right unit in front of you. Whether the control unit is actually defective, or a plug or cable is the cause, only the fault memory will show. Have it read out in advance.

For the same vehicles, we also repair control units with the part numbers 28555-3E121, 98820-3TA0B, 98820-3TA9C, 98820-9HN0A, 98820-9HS9A, 98820-JA100.

How does the repair of the 28556 ZB201 work?

You have the fault memory read out, attach the log, disconnect the battery and only then remove the control unit. Then you create a repair order online and send the unit in. Airbag24 checks, repairs and tests it, then it goes back to you.

The order of these steps protects you during removal: the control unit is only released after the battery has been disconnected.

At Airbag24 the unit is checked, defective components are repaired, crash data is erased and a function test follows. Processing usually takes 3–4 working days.

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 ZB201 get to Airbag24?

You send the control unit 28556 ZB201 as a parcel, or you book a UPS collection for an extra charge. After the repair, Airbag24 sends it back by UPS.

Put the printed repair order into the parcel and pack the unit shock-proof.