The National Highway Traffic Safety Administration (NHTSA) has opened a formal investigation into 416,000 Tesla cars over reports of unexpected brake activation related to a driver assistance system called Autopilot.
The initial investigation includes Tesla Model 3 and Model Y vehicles made in 2021-2022 in the United States (US).
The investigation comes after NHTSA received 354 complaints about the matter in the past nine months. NHTSA says the vehicle under review has an advanced driver assistance system Tesla is calling Autopilot. This feature allows the car to brake and drive automatically in its lane.
“Complainants report that rapid deceleration can occur without warning. Randomly and frequently repeatedly within a single drive cycle,” said NHTSA.
The owner of a 2021 Tesla Model Y told NHTSA last October, while driving down the highway at 80 miles per hour the car suddenly slowed to 69 miles per hour in less than a second.
The braking was so hard that it almost made the driver lose control.
The NHTSA investigation into Tesla is not the first. In August 2021, NHTSA conducted a formal safety investigation into Tesla's Autopilot system on 765,000 vehicles in the US.
Earlier this month, NHTSA confirmed that it was reviewing consumer complaints regarding Tesla cars unnecessarily activating the brakes. The initial evaluation is the first stage before NHTSA can issue a formal withdrawal request.
In May last year, Tesla Chief Executive Elon Musk said removing the radar sensor from the partially automatic drive system would solve a braking problem known as phantom braking. Phantom braking has long been a complaint of some Tesla drivers.
There is no explanation from Tesla. The auto company, which has dissolved its media relations department, did not respond to requests for comment.
Tesla has come under increasing scrutiny from NHTSA which is investigating several issues. Tesla has issued 10 vehicle recalls since October 2021. Some recalls are under pressure from NHTSA.
In November last year, Tesla recalled nearly 12,000 US vehicles sold since 2017. A miscommunication could lead to an incorrect collision warning or unexpected activation of the emergency brakes.