The National Highway Traffic Safety Administration is investigating nearly 1.3 million Ford F-150 pickup trucks in the United States over reports of an unexpected gear downshift accompanied by a temporary rear wheel lock-up.

The problem could affect nearly 1.3 million F-150 trucks. Ford is cooperating with the investigation as the NHTSA determines the scope and severity of the potential issue. No injuries or crashes have been reported in connection with the customer complaints.