The contact owns a 2015 Kia Optima. The contact stated while driving approximately 75 MPH, the vehicle independently decelerated to approximately 60 MPH. The contact stated that the check engine warning light was flashing. The vehicle was towed to the local dealer, but the cause of the failure was not yet determined. The contact stated that a knock sensor was installed to monitor the engine performance. The manufacturer was not yet contacted regarding the failure. The failure mileage was 70,000. The VIN was not available.