Airbag control unit with part number 89170-50K40

What does the airbag control unit 89170-50K40 do?

The airbag control unit 89170-50K40 is the central control unit of the SRS restraint system of Lexus. It evaluates crash sensors and decides within milliseconds in an accident which airbags and seatbelt pretensioners are triggered.

The unit monitors the function of the system continuously and reports faults via the airbag warning light.

After an accident it stores crash data and locks itself.

Why does the control unit 89170-50K40 fail?

The most common cause is stored crash data after an accident, even if no airbag has deployed; a standard diagnostic tool cannot clear it. Other causes include aged components, cold solder joints, moisture at plug connections and voltage spikes.

Crash data remains in the unit until it is erased during the repair. It arises regardless of whether an airbag deploys.

The other causes affect the electronics themselves. Components age over time, solder joints can go cold, and moisture or corrosion damage plug connections.

Voltage spikes, for example from a weak battery or a jump-start, can likewise cause a failure.

How can you tell that the 89170-50K40 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently. Further signs include fault messages, a missing connection to the diagnostic tool and a fault memory that cannot be cleared. In such cases airbags and seatbelt pretensioners may possibly fail to deploy in an emergency.

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

The warning light is the direct indication from the vehicle of a fault in the restraint system. Have such signs checked before you rely on the system.

Which vehicles is the 89170-50K40 fitted in?

The 89170-50K40 is fitted in these vehicles: Lexus LS XF50 (from 2018).

For this part number we have the following vehicles on record:

• Lexus LS XF50 (from 2018)

Before sending it in, two checks are worthwhile. Compare the part number on the label of the removed unit with this page; this only ensures that it is the right unit. Also have the fault memory read out beforehand, because only that shows 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 89170-50K81, 89170-50K83, 89170-50L00, 89170-50L03, 89170-53790, 89170-53820.

How does the repair of the 89170-50K40 work?

For the 89170-50K40, first have the fault memory read out and attach the log, then disconnect the battery and only then remove the control unit. Afterwards create a repair order online and send the unit in well packed.

Airbag24 examines the unit on the test bench, replaces defective components, erases stored crash data and carries out a function test. 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 89170-50K40 get to Airbag24?

You send the control unit 89170-50K40 as a parcel or book a UPS collection for an extra charge. After the repair Airbag24 sends it back to you by UPS.

Pack the control unit shockproof and place the printed repair order in the parcel before you send it.