One problem related to anti-theft controller has been reported for the 2004 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Hyundai Sonata based on all problems reported for the 2004 Sonata.
Sub frame on front passenger rusted and corroded. Caused damange to cv axle on same side. Caused alignment issues on front end. Causes tires to wear quickly, within a week. Anti theft system locks the car while driving and causes alarm to sound while driving and must open other doors and stop driving to stop the alarm from going off, headlights and dash lights and tail lights come on when brake is pressed and go off when brake is released but this problem only happens when headlights are not in use.