The National Highway Traffic Safety Administration says it has launched an investigation into the safety of Tesla’s Full Self-Driving feature, or FSD, after at least one fatal accident involving a pedestrian.

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

The U.S. automotive safety regulator has opened a new investigation into Tesla's Full Self-Driving (Supervised) software after four reported crashes in low-visibility situations.

Four crashes and one death could lead to a costly recall or FSD being banned.

Officials are looking into whether self-driving systems in Tesla vehicles are safe in fog, glaring sun or other "reduced roadway visibility conditions," the National Highway Traffic Safety Administration said Friday.

A federal investigation into Tesla was announced Thursday after one person was injured, and one died after a crash involving a self-driving Tesla.

Driving' appears to struggle in low visibility situations and has led to four crashes, including at least one death. Now it's under investigation.

Tesla's Full Self-Driving system is being investigated in the US after reports it may not function properly when visibility on the road is poor.

The National Highway Traffic Safety Administration said in documents that it opened the probe Thursday after the company reported four crashes when Teslas encountered sun glare, fog and airborne dust.

More than 2.4 million Tesla electric vehicles have been placed under investigation by an automotive regulator over fears collisions could occur during poor weather conditions. The United States National Highway Traffic Safety Administration (NHTSA) has launched an investigation into Tesla's popular Full Self-Driving (FSD) technology.