A Tesla Model S is displayed during the London Motor and Tech Show at ExCel on May 16, 2019 in London, England.

According to a notice published on Tuesday, the U.S. National Highway Traffic Safety Administration (NHTSA) has opened an investigation into Tesla over a possible defect in Model S and Model X battery packs that could cause "non-crash fires."

A defect petition submitted to NHTSA by consumer attorney Edward Chen prompted the investigation.

Chen filed the petition on behalf of Tesla owners, including his client David Rasmussen, after Tesla pushed over-the-air software updates to some vehicles, which reduced the range the electric cars could travel on a single charge, owners said.

The petition complained that the software updates, which started in May 2019, were not an appropriate fix for batteries that could ignite in non-crash scenarios.

Chen wrote, in a letter submitted to the Department of Transportation and NHTSA, accompanying the petition: "Tesla is using over-the-air software updates to mask and cover-up a potentially widespread and dangerous issue with the batteries in their vehicles."

Following the investigation into the battery fire and throttling issues, NHTSA will either decide to issue a recall-- which would be financially burdensome to Tesla and could tarnish its reputation-- or is required to publish its findings in the federal register if a recall is not necessary.

Tesla is striving to reduce the costs of its batteries. In the past two years, the company struggled with waste and quality control at its giant battery plant, the Gigafactory, outside of Reno, Nevada.

Representatives from Tesla did not respond to requests for comment.

In 2016, Tesla CEO Elon Musk said that he believed most safety complaints filed to NHTSA were "fraudulent" and suggested such complaints were part of a broad conspiracy to thwart his electric vehicle company.

Musk tweet 1

Tesla's new Smart Summon feature (which allows drivers to bring a car out of a parking spot to where they are standing without a driver behind the wheel) also caught the attention of NHTSA this week. The agency said it became aware of some reports of accidents involving Smart Summon but declined to confirm whether it has launched a formal investigation into Smart Summon.

Here's the full petition: