One problem related to front suspension upper arm has been reported for the 1999 Hyundai Sonata. The most recently reported issues are listed below.
The contact owns a 1999 Hyundai Sonata. While driving 30 mph, the passenger side front wheel collapsed and the vehicle stopped. The vehicle was towed to a local mechanic and he stated that the front upper control arm was rusted and the bolts separated from the frame. The vehicle was towed to the dealer and they were unable to diagnose the cause of failure. The contact felt that the failure was a manufacturer defect. The current and failure mileages were 69,000.