The National Highway Traffic Safety Administration's (NHTSA) assessment covers 2.4 million Tesla vehicles of various models produced between 2016 and 2024.
The NHTSA's action is the first step toward a possible recall that the agency could seek from the company run by tech billionaire Elon Musk.
Tesla did not immediately respond to a BBC inquiry about the investigation.
The NHTSA's preliminary assessment was made after four accident reports related to Tesla's use of its "Full Self-Driving," or FSD, software.
The agency said the crashes were related to reduced roadway visibility, fog or glare from the sun.
In one of the crashes, a Telsa fatally struck a pedestrian, and in another, someone was injured, NHTSA said.
The evaluation is intended to determine whether Tesla's self-driving systems can detect and respond appropriately in reduced visibility conditions. It will also examine whether other crashes involving self-driving cars have occurred under similar conditions.
In its notice, the agency notes that despite the label, full self-driving is actually a "partial driving automation system."
NHTSA's announcement comes a week after the glamorous unveiling of the Musk-created cybercab at the Warner Bros. studio site in Burbank, Calif.
During the event, he said the concept for a fully autonomous robo-taxi that operates without pedals and a steering wheel will be on the market by 2027.
However, some analysts and investors were not impressed.
The company's stock dropped 8% after the vehicle was unveiled. The stock was mostly steady after the NHTSA announcement.
Unlike Waymo, the self-driving venture run by Alphabet, Google's parent company, Tesla's autonomous systems rely heavily on cameras and artificial intelligence.
Musk's approach costs less than deploying high-tech sensors like Lidar and radar, which are critical to Waymo's driverless car program. | BGNES
