The agency has received complaints that doors are continuing to open while driving in vehicles that have already received new software to address the issue.

The National Highway Traffic Safety Administration has opened an investigation into a Land Rover recall that may not have succeeded in addressing a problem with door latches.

The company initially recalled the 2013-2016 Range Rover and 2014-2016 Range Rover Sport to fix a problem that allowed the doors to open while driving. The fix involved a software update for the Keyless Vehicle Module that controls the rear door latches.

The agency has received four complaints alleging incidents of doors opening while driving in vehicles that either received the software update or entered production after the new programming was introduced on the assembly line.

"The incidents reported to ODI have involved the driver's door (1), front passenger side door (2) and rear passenger side door (1)," the NHTSA says. "The latter incident allegedly resulted in an injury to an adult occupant, who sustained fractured ribs when reaching over a child's car seat 'to keep the child from falling from the moving vehicle.'"

In each of the four incidents, the problem was fixed by installing the latch assembly for the problematic door.

The NHTSA is presumably attempting to determine if the recall was botched and should have involved installation of new latch hardware from the beginning, instead of the simpler -- and much less expensive -- adjustments to control module programming.