The contact owns a 2011 Buick Lacrosse. The contact stated while the vehicle was at a complete, his son was rear-ended by another vehicle. The air bag warning light illuminated on the instrument panel; however, the air bag did not deploy. As a result, the driver hit his head on the headrest. The driver did seek medical attention for his injury. A police report was filed. The vehicle was drivable. In addition, the seat belt retractor latches were not able to be used after the rear-ended accident. The manufacturer and dealer were not notified of the failure. The approximate failure mileage was 135,000.