One problem related to transmission slip out of gear has been reported for the 2001 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Hyundai Sonata based on all problems reported for the 2001 Sonata.
Failure of transmission to shift, or drop out of gear at highway speeds. Told it is the input speed sensor. Common failure on this vehicle.