Highway regulators are investigating complaints of alleged suspension-failure issues in an estimated 1.2 million Tesla vehicles.

The National Highway Traffic Safety Administration said it has received 156 complaints alleging suspension failure in Tesla's model year 2018 to 2020 Model 3s, as well as in 2021 to 2023 Model Y vehicles.

The issue involves the detachment of the front lower lateral link, which potentially causes a loss of vehicle directional control, the regulator said. In most cases, there was no advance warning or indication that the suspension failure would occur, the NHTSA said.

Tesla previously recalled vehicles for lateral-link detachments, the regulator noted. But the subject failures for this investigation go beyond the scope of those previous recalls and don't appear to be related to the production issue that prompted those prior recalls, it said.