The Federal Motor Carrier Safety Administration has closed its investigation into a heavily publicized crash of a TuSimple autonomous truck.

TuSimple said it responded to several FMCSA requests following the April 6 non-injury incident on Interstate 10 in Arizona. The probe closed with no penalties. The National Highway Traffic Safety Administration declined to open a separate probe, the company said.

A driver-supervised autonomous truck took an unintended sharp left turn across a lane of westbound traffic on I-10 and struck a concrete barrier. The safety driver tried to countersteer the truck, which followed a computer-generated command that was several minutes old.

TuSimple initially said the incident was driver error. Later it acknowledged its compute system and the safety driver both bore responsibility. The company grounded its fleet of mostly Navistar International trucks and made software fixes to avoid a repeat occurrence.