More than 750 Tesla owners have filed complaints with the US Safety Regulatory Authority about sudden stops on the road, for no apparent reason, in cars with partially automated steering systems.

The US National Highway Traffic Safety Administration (NHTSA) released the number of complaints Friday in a letter requesting information from the vehicle’s manufacturer.

The 14-page document, dated May 4, requires Tesla to submit all customer reports about “stealth” brakes, as well as reports of accidents, injuries, deaths and property damage claims.

The regulator also questioned whether “full autonomous driving” and automatic emergency braking systems were active at the time of any of these accidents.

That agency began investigating “stealth” braking on Tesla Models 3 and Y in February, after receiving 354 complaints, involving about 416,000 vehicles from 2021 and 2022. At the time, the agency said it had no reports of accidents or injuries.

In communication with the company founded by Elon Musk, a deadline has been set until June 20 to fulfill the request for information, although it is indicated that Tesla may have requested an extension.

Tesla stock. It fell more than 9% on Friday and the company did not respond to requests for comment from the Associated Press (AP).

The agency explained that the investigation includes vehicles equipped with automated driver assistance features, such as adaptive cruise control and “autopilot”, which allow them to brake automatically and steer to the lane.

“Complaints indicate that rapid deceleration can occur without warning and often repeatedly during a single driving cycle,” the regulator added.

This is the fourth official investigation of the Texas manufacturer in the past three years, and NHTSA is overseeing 23 recalls. [chamadas dos veículos à fábrica] Tesla since January 2021.

The agency is also investigating complaints about automatic emergency braking systems on more than 1.7 million Honda vehicles, which can stop vehicles without cause.

In addition, NHTSA has a broader investigation underway into accidents involving partially automated driving systems across all manufacturers.

Fifteen people have died in the accidents investigated by the NHTSA, and at least 15 others have been injured. Of the deaths, 14 were in Tesla-related accidents, according to agency documents.