The NHTSA is exploring possible links to a previous Fiat Chrysler Automobiles recall.
The National Highway Traffic Safety Administration has launched an investigation into the Hyundai Sonata and Kia Forte after identifying several fatal accidents associated with a potential airbag defect.
The agency is aware of at least six frontal crashes in which airbags failed to deploy despite significant collision-related damage. The accidents resulted in four fatalities and six injuries.
Notably, Hyundai already filed a defect report identifying an electrical overstress condition in the airbag control units (ACUs) removed from three of the crashed vehicles. The ACUs were supplied by ZF, suggesting other makes and models could be affected if the same modules were used beyond the 2011 Sonata and 2012-2013 Forte.
"Additionally, [the Office of Defects Investigation] is aware of a prior recall ... where [electrical overstress] appeared to be a root cause of airbag non-deployment in significant frontal crashes in certain Fiat Chrysler vehicles," the NHTSA says.
The agency will now evaluate Hyundai's root-cause analysis and determine if a wider recall campaign is warranted.