DETROIT (AP) — U.S. auto safety regulators have expanded an investigation into malfunctioning air bag controls to include 12.3 million vehicles equipped with bags that may not inflate in a crash. The problem could be responsible for as many as eight deaths.

Vehicles made by Toyota, Honda, Kia, Hyundai, Mitsubishi and Fiat Chrysler from the 2010 through 2019 model years are included in the probe, which was revealed Tuesday in documents posted by the National Highway Traffic Safety Administration. It involves air bag control units made by ZF-TRW that were installed in the vehicles.

The control u...