Airbag control unit with part number 89170-F4850

What does the airbag control unit 89170-F4850 do?

The airbag control unit 89170-F4850 is the switching centre of the restraint system (SRS) for Toyota. Using the crash sensors, it detects an accident and triggers the intended airbags and seatbelt pretensioners within fractions of a second.

During normal operation, the unit continuously evaluates the system states. It reports a fault via the airbag warning light in the instrument cluster, so that the driver can react.

In an accident, the control unit records crash data and locks itself. The lock is only lifted by the repair.

Why does the control unit 89170-F4850 fail?

Stored crash data after an accident is the most common cause, even without a deployed airbag. A normal diagnostic tool cannot remove it. Ageing electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes are also possible causes.

The crash data is caused by the registration of an event. Whether an airbag ignited does not matter for the storage, because the entries remain.

The other causes relate to ageing and environmental influences. Electronics wear out, solder joints can stay cold, and plug contacts corrode when moisture gets in. A weak battery or a jump start can also cause voltage spikes that damage the unit.

How can you tell that the 89170-F4850 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently. Also possible are a fault message in the instrument cluster, a missing connection between the diagnostic tool and the control unit, and a fault memory that cannot be cleared.

The warning light is the clear signal that something is wrong in the restraint system. In an emergency, the airbags and seatbelt pretensioners may then fail to deploy, so prompt action is important.

A missing diagnostic connection is also a clear finding. A detailed examination will establish the cause.

Which vehicles is the 89170-F4850 fitted in?

The control unit 89170-F4850 is fitted in these vehicles: Toyota C-HR NGX50 (from 2024). With this information you can check before removal whether the unit belongs to your vehicle.

The following list shows the vehicles for which this unit is intended.

• Toyota C-HR NGX50 (from 2024)

Compare the part number on the label of the removed unit with this page. This ensures that it is the correct unit, but the comparison does nothing more. Also have the fault memory read out in advance, because only this log 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 89170-F4210.

How does the repair of the 89170-F4850 work?

First have the fault memory read out, enclose the log and then disconnect the battery. Only then remove the control unit. Processing at Airbag24 usually takes 3–4 working days.

Then create a repair order online. Pack the unit well before you send it.

At Airbag24, the unit is tested on the test bench, defective components are replaced, crash data is erased and a function test is carried out. Your own unit is then returned 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 89170-F4850 get to Airbag24?

You send the control unit 89170-F4850 as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 sends it back to you by UPS.

Put the printed repair order in the parcel and pack the unit shockproof.