On the 2.7L V6 and 2.4L 4 Cylinder, a defective exhaust gas recirculation (EGR) switching valve may cause an intermittent rough or unstable idle engine.
Problems for specific Hyundai Sonata years:
Car problem reports
Problem with your car? See what our experts say or submit your own.
Most reported 1999 Hyundai Sonata problems
Concerned about safety, the NHTSA is investigating reports of rust forming at the front suspension mounting points, the frame, and the sub-frame. Some of these vehicles may have been recalled for this issue. For more information, please click here»
If the automatic transmission does not shift properly and the Check Engine Light illuminates, the speed sensors in the transmission may have failed. The sensors are simple and inexpensive to replace.
Premature timing belt failure may result in serious engine damage. When replacing a broken timing belt, it is important to inspect and possibly replace the crankshaft position sensor; it is often damaged when the timing belt breaks.