United States decides not to open formal probe of Tesla battery fires

US automobile safety regulators have denied a petition seeking an investigation into Tesla software updates, saying it's unlikely a probe would find a safety defect.

The National Highway Traffic Safety Administration on Monday denied the 2019 petition, which alleged that over-the-internet software updates cut battery range in response to battery fires across the globe.

The agency said in documents posted in the Federal Register that it found a pattern of fires in China after the vehicles were charged up at Supercharger fast-charging stations. But no similar fires were identified in the US.

Three non-crash fires outside of China that were cited in the petition either did not start in the battery or were not related to fast charging, the agency said. Two of those were in the US.

The agency said that it won't open a formal investigation into the fires and the software update.

The available data indicate that noncrash battery fires in Tesla vehicles are rare events, NHTSA wrote.

It is unlikely that an order concerning the notification and remedy of a safety-related defect would be issued due to any investigation opened as a result of granting this petition."

NHTSA said it looked into data from the petition and from Tesla, and it examined field data from noncrash fires.

The inquiry covered about 255,000 Tesla Model S and X vehicles from the 2012 through 2019 model years.