Tesla Self-Driving System Will Be Investigated by Safety Agency

The National Highway Traffic Safety Administration said it was looking into what Elon Musk’s electric car company called the full self-driving system.

Tesla’s plan to build fleets of self-driving cars suffered a setback on Friday when the main federal auto safety regulator said it was investigating whether the technology was to blame for four collisions, including one that killed a pedestrian.

The regulator, the National Highway Traffic Safety Administration, said it was examining whether the software, which Tesla calls supervised full self-driving, had safeguards in place to require drivers to retake control of their cars in situations the autonomous technology could not handle on its own.

As sales of Tesla’s electric cars have slowed, Elon Musk, the company’s chief executive, has staked the company’s future on software that allows cars to navigate, steer and brake without human supervision. Last week, the company held an event at the Warner Bros. studios near Los Angeles to unveil what it called a cybercab, which Mr. Musk promised would be able to ferry passengers without a human driver.

But such software has faced persistent criticism from regulators and safety experts who say it does not do enough to make sure drivers remain alert and ready to take over if the system makes a mistake. Tesla faces numerous lawsuits from people who blame the software for injuries or deaths of loved ones.

Tesla did not respond to a request for comment.

The crashes highlighted by the safety agency on Friday took place when road visibility may have been limited by glare from the sun, fog or dust, the federal safety agency said. Tesla’s self-driving software depends on cameras to operate, unlike other manufacturers who also use radar or laser technology that are often better at detecting objects and people when the view is obscured by poor weather or bright sunshine.

The agency said it would “examine the system’s potential failure to detect and disengage in specific situations where it cannot adequately operate.”

In one of the collisions, a pedestrian died. In another, a person was injured, the agency said.

The investigation covers 2.4 million Tesla vehicles, including cars manufactured as far back as 2016. All of Tesla’s passenger models are involved, the agency said, including the Model 3 and Model S sedans, the Model X and Model Y sport utility vehicles, and the Cybertruck.

Federal officials have also been investigating a less capable Tesla system known as Autopilot for several years. These investigations may not survive if former President Donald J. Trump is elected next month. Mr. Trump has said he will appoint Mr. Musk, one of his most prominent supporters in the business world, to lead a “government efficiency commission.”