The National Highway Traffic Safety Administration (NHTSA) on Wednesday questioned why Tesla did not recall autopilot software that it updated to identify parked emergency vehicles.
Safety investigators wrote a letter to the electric carmaker saying its vehicles must be recalled if an over-the-internet update resolves a former safety defect, The Associated Press reported.
“Any manufacturer issuing an over-the-air update that mitigates a defect that poses an unreasonable risk to motor vehicle safety is required to timely file an accompanying recall notice to NHTSA,” the NHTSA wrote to Eddie Gates, Tesla’s director of field quality, according to the AP.
The safety agency also demanded that Tesla disclose more information about its "Full Self-Driving" software, the AP also reported.
The NHTSA's letter is the latest sign of the agency's ongoing tensions with Tesla.
In August, federal investigators said they would launch a formal investigation into the automaker's Autopilot software after a series of crashes involving emergency vehicles. The letter cited 12 incidents in which Tesla vehicles operating in Autopilot or cruise control ran into first responder vehicles.
At that time, the National Transportation Safety Board had also investigated some of the crashes and recommended limiting when and where Autopilot features can be used, but it lacked the authority to enforce any software changes.
The Hill has reached out to the NHTSA and Tesla for comment.