Toyota has been aware of the problem since October of 2007, and changed the software in new vehicles in 2008, and yet did not recall the defective vehicles even though injuries were reported. Previous such coverups resulted in record fines imposed on Toyota by NHTSA in 2010 for failure to act promptly on a safety defect.

In the side curtain airbag system of the defective Rav4 and Highlander models, there are two sensors, which are designed to detect vehicle roll angle. If one of these sensors malfunctions, the airbag warning light will illuminate and the roll detection system will be suspended. However, the side curtain airbag remains available in the event of a side collision.

If both sensors fail nearly simultaneously after the initial airbag system check, the seat belt pretensioner could activate as the curtain airbag blows up – the reason for the Toyota recall.