While the recall is hefty at nearly 1 million vehicles, the risk that these vehicles contain the defect is small. Hyundai estimates just 1% of these vehicles actually have the defect.

The recall covers certain 2011-2014 Sonata and 2011-2015 Sonata Hybrid vehicles.

The automaker reported to U.S. safety regulators that in the affected vehicles, the seat belt linkages for both front seat belts may detach from the seat belt anchor pretensioners.

Hyundai Sonata vehicles have a seat belt anchor pretensioner that is fastened to the inner sill structure of the sedan. When the vehicle is being assembled, the anchor pretensioner is fastened to the sill prior to being connected to the seat belt linkage.

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If, during vehicle assembly, the connector does not fully latch when the linkage is pressed onto the connector, the seat belt can detach from the anchor pretensioner. If the anchor pretensioner isn’t correctly connected to the seat belt linkage it could separate or detach during a collision, which increases the risk of injury.

Hyundai and the seat belt supplier continue to investigate this issue, the company said in its filing with the U.S. National Highway Traffic Safety Administration.