Mazda first became aware of the problem in November 2022. A second report of vehicles suddenly losing power steering assist followed a month later.In March 2023, the Japanese automaker determined that the problem was caused by grease extruding from the gear teeth. In light of this discovery, the company modified the shape of the worm gear’s teeth so that gear grease would not spill out.

By September 2023, however, Mazda realised that the countermeasure was not having the desired effect. The improved component continued to fail, prompting Mazda to consider further improvements.In December 2023, Mazda determined that excessive spring force was causing grease to be extruded, resulting in a sticky condition. The improvement was to reduce the spring force applied to the worm gear.

Mazda has not received reports of accidents or injuries related to this failure in its CX-90 models, but from October to December 2023, Mazda received five reports of sudden loss of power steering assist from the U.S. market. The improved steering assembly went into production in December 2023 at the Hofu plant in Japan.

The recalled vehicles were manufactured from 27 December 2022 to 11 December 2023. Dealers have now been instructed to replace the spring that engages the worm gear with the improved part and to re-grease the gear teeth. And CX-90 owners will be notified by mail by 18 March at the latest.