Toyota bZ4X Touring airbag control unit repair

What is a Toyota bZ4X Touring airbag control unit?

In the Toyota bZ4X Touring, the airbag control unit is the central control unit of the restraint system (SRS). It reads the signals from the crash sensors and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners deploy. It also monitors the system continuously and reports faults via the airbag warning light.

The unit is fitted in the Toyota bZ4X Touring (since 2026); the manufacturer of the control unit is given as Denso. As soon as you switch on the ignition, a self-test runs in which the control unit also queries the connected components. If anything fails to respond or responds incorrectly, the warning light stays on.

If there has been an accident, the control unit stores crash data and locks itself.

Why is the Toyota bZ4X Touring airbag control unit defective?

The cause is usually crash data stored in the unit after an accident, even if no airbag deployed; an ordinary diagnostic tool cannot remove it. Other triggers are aged components, cold solder joints, moisture with corrosion on the connectors and voltage spikes in the vehicle electrical system.

It starts with the accident: the stored crash data keep the control unit locked, even if the vehicle shows hardly any outward damage. Independently of this, ageing becomes noticeable over the years. Electronic components deteriorate, and fine cracks form in solder joints, making contact only intermittently.

Moisture adds to this. If water reaches the plug connections, corrosion forms and the signals arrive disturbed. Finally, the vehicle electrical system itself can cause damage: a weak battery or jump-starting produces voltage spikes that put stress on the sensitive electronics in the control unit.

A fault usually shows itself like this: the airbag warning light stays on continuously, the fault memory cannot be reset, or the diagnostic tool cannot find a connection to the control unit. In this case, first read out the fault memory.

Common error codes for Toyota bZ4X Touring airbag control unit repair

In the Toyota bZ4X Touring, the codes point to internal faults of the control unit, interrupted communication, disturbed firing circuits of the airbags or problems with occupant detection. They are stored in the fault memory of the airbag control unit, and a diagnostic tool reads them out.

The codes that occur in the Toyota bZ4X Touring include the following:

• B1000 → Internal fault in the airbag control unit
• B1100 → Internal fault in the airbag sensor unit
• U0151 → Communication with the airbag control unit lost
• B1800 → Firing circuit of the driver airbag disturbed
• B1805 → Firing circuit of the passenger airbag disturbed
• B1650 → Occupant detection fault

The codes are read out with a diagnostic tool. A single code does not reliably tell you whether the control unit is really defective, since connectors, wiring or an airbag module may equally be the cause. Only the inspection shows where the fault lies.

What part numbers are available for the Toyota bZ4X Touring airbag control unit repair?

You will find the part number on the label of your airbag control unit; it determines the exact version. Depending on equipment and year of manufacture, the numbers differ within a model series.

Take the number from the label of your removed unit and enter it in the repair order. Airbag24 uses this information to identify the version. Whether the unit is defective is only clarified by reading out the fault memory or by the inspection.

The route to repair: have the fault memory read out, disconnect the battery and remove the control unit. Then create a repair order online and send the unit in. At Airbag24, checking, repairing and testing usually take 3–4 working days. You receive your own unit back.

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.