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.Google+
Car Problem Reports
Hyundai Sonata Rough Idle Due to Faulty EGR Switching Valve
Hyundai Sonata Problem
Engines Affected: 2.0L 4 Cylinder, 2.4L 4 Cylinder, 2.5L V6, 2.7L V6, 3.3L V6
Average Mileage: 105,047 mi (11,386 mi - 200,000 mi)
engine idles rough when in drive but not in neutral
Visitor, 2001 Hyundai Sonata, 2.4L 4 Cylinder, 110,000 mi
Rough idle, lack of acceleration at times, and poor gas mileage.
Visitor, 2004 Hyundai Sonata, 2.4L 4 Cylinder, 37,000 mi
Rough idle when stopped. Car shakes a lot.
engine light indicated need to repalce EGR valve. Did so a a week later it says the same thing again and idle is rough again. Why????
Visitor, 2002 Hyundai Sonata, 2.4L 4 Cylinder, 150,000 mi
Rough idle and engine seems very rough while accelerating from a dead stop. Runs well at cruising speed. Only seem rough when the engine is under load.
Visitor, 2003 Hyundai Sonata, 2.4L 4 Cylinder, 45,600 mi
Rough and unstable engine. Feels like gas is choked from engine or loose battery wires. Then car takes off. Scary! Not fixed yet
Visitor, 2004 Hyundai Sonata, 2.4L 4 Cylinder, 116,000 mi
She runs ruff when idleing and even worse if the a/c is running . The shaking slows down if i put her in drive or neutral.
Roough idle, jerks a little when driving, began to stall. Will change Throttle Position Sensor and see what happens.
Visitor, 2004 Hyundai Sonata, 2.4L 4 Cylinder
Failed emissions due to egr
Visitor, 2002 Hyundai Sonata, 2.7L V6, 100,695 mi
Check engine light, rpm fluctuations, shakes at stoplights. Also, has stalled when getting gas.