US asks Tesla why it didn't recall Autopilot driving system

U.S. highway safety investigators want to know why Tesla didn’t file recall paperwork when it updated Autopilot software so it would do a better job spotting parked emergency vehicles

DETROIT -- U.S. highway safety investigators want to know why Tesla didn't file recall paperwork when it updated Autopilot software so it would do a better job spotting parked emergency vehicles.

In a letter sent to Tesla on Tuesday, the National Highway Traffic Safety Administration told the electric car maker that it has to do a recall if an over-the-internet update mitigates a safety defect.

“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 agency said in a letter to Eddie Gates, Tesla’s director of field quality.

The agency also ordered Tesla to provide information about its “Full Self-Driving” software that's being tested on public roads with some owners.