Airbag control unit with part number 89170-F4540

What does the airbag control unit 89170-F4540 do?

The airbag control unit 89170-F4540 is the central control unit of the restraint system (SRS) of Toyota. It evaluates the signals from the crash sensors, decides in an accident within milliseconds on the triggering of airbags and seatbelt pretensioners, and monitors the system continuously.

The unit reports faults via the airbag warning light. After an accident it also stores crash data and locks itself.

The function is therefore divided in two: in an emergency the unit controls the restraint devices, and afterwards it keeps a record of what happened.

Why does the control unit 89170-F4540 fail?

The most common cause on the 89170-F4540 is crash data stored after an accident, even without a triggered airbag. Ageing components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes come into consideration in addition.

Crash data cannot be removed with an ordinary diagnostic tool. Airbag24 erases it during the repair.

The other causes concern the electronics and their connections. Electronics age, solder joints can turn cold, and moisture attacks plug connections. Voltage spikes arise, for example, from a weak battery or jump-starting.

How can you tell that the 89170-F4540 is defective?

A defect on the 89170-F4540 shows itself through the airbag warning light in the instrument cluster, which stays on permanently or intermittently. Signs in addition are an error message in the instrument cluster, a missing connection to the diagnostic tool and a fault memory that cannot be cleared.

Each of these signs means that airbags and seatbelt pretensioners may not deploy in an emergency. The signs in detail:

• Airbag warning light stays on permanently or intermittently
• Error message in the instrument cluster
• Diagnostic tool receives no connection to the control unit
• Fault memory cannot be cleared

Which vehicles is the 89170-F4540 fitted in?

Before removal, check your vehicle against the overview. The control unit 89170-F4540 is fitted in these vehicles: Toyota C-HR NGX10 Facelift (2019-2023).

This overview shows the vehicles:

• Toyota C-HR NGX10 Facelift (2019-2023)

Comparing the part number of the removed unit with this page only confirms that it is the right unit. Having the fault memory read out is a separate step: only that result shows whether the control unit is defective or a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 89170-F4210, 8917010110.

How does the repair of the 89170-F4540 work?

First have the fault memory read out and attach the log. Then disconnect the battery and only then remove the control unit 89170-F4540. Processing at Airbag24 usually takes 3–4 working days.

The sequence is binding for safety reasons. Next create a repair order online.

At Airbag24 the unit is checked on the test bench, defective components are repaired or replaced, the crash data is erased and a function test follows. Your own unit then goes 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 89170-F4540 get to Airbag24?

Your 89170-F4540 is sent to us as a parcel, or you book a UPS collection for an extra charge. After the repair Airbag24 returns the unit to you by UPS.

Enclose the printed repair order and pack the unit shock-proof.