The National Highway Traffic Safety Administration said it has opened an investigation into nearly 2.9 million Tesla vehicles after reports of traffic safety violations linked to the electric car maker’s Full Self-Driving system, according to a filing on the government regulator’s website.

The probe by the agency’s Office of Defects Investigation involves Tesla vehicles equipped with “FSD (Supervised)” and “FSD (Beta)” versions of the the company’s self-driving systems. Both require “a fully attentive driver who is engaged in the driving task at all times,” NHTSA said in a document filed as part of the probe. 

Reports of traffic violations include vehicles operating with FSD driving through red traffic signals and initiating lane changes into opposing traffic. 

NHTSA has received reports of 58 safety violations linked to Tesla vehicles with FSD. Those incidents include more than a dozen crashes and fires, along with 23 injuries, according to the agency.

U.S. regulators have been investigating Tesla’s automated driving systems for more than three years because of dozens of crashes that raised safety concerns, such as a Seattle-area Tesla crash in 2024 involving Full Self-Driving that killed a motorcyclist. 

“The ultimate question is, ‘Does the software work?'” asked Seth Goldstein, a Morningstar analyst with a “sell” rating on Tesla shares stock. 

Such problems have led lawmakers and safety regulators to question whether Tesla’s automated system and other like it will ever be able to operate safely on a widespread scale. A new law in California that would hold driverless car companies accountable for traffic violations is set to take effect next year.

Tesla is also under investigation by NHTSA for a “summon” technology that allows drivers to tell their cars to drive to their location to pick them up, a feature that has reportedly led to some fender benders in parking lots. A probe into driver-assistance features in 2.4 million Teslas was opened last year after several crashes in fog and other low-visibility conditions, including one in which a pedestrian was killed.

Another investigation was launched by NHTSA in August looking into why Tesla allegedly has not been reporting crashes promptly to the agency as required by its rules. 

CEO Elon Musk is under pressure to show that the latest advances in its driver-assistance features have not fixed such problems. He recently promised to put hundreds of thousands of such self-driving Tesla cars and Tesla robotaxis on roads by the end of the next year.

Tesla shares fell 1.4% Thursday. The company did not immediately respond to a request for comment.