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.
2004 Hyundai Sonata Problem Reports
Most Reported 2004 Hyundai Sonata Problem Reports
Problems with the accelerator pedal position switch may cause the Check Engine Light to illuminate; an improved switch is available to fix this problem.
If you experience excessive engine noise on startup (after the engine has been turned off for several hours) that lasts for more than five or six seconds, turn off the engine and check that the engine oil level is correct. If the oil level is correct, the noise may be caused by the timing chain tensioner. Hyundai has an improved tensioner to correct this problem.
Parking lights not turning off intermittently or all the time. The common problem is with the cabin fuse box. Complete replacement of the assembly is necessary to fix the problem.
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.
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»
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.