Elantra EGR Valve Issue

That sounds very familiar. I have an Elantra too, and went through something similar not too long ago. The symptoms you describe – the check engine light, the rough idling, even the smoke under acceleration – all point to a possible EGR valve issue. Did you happen to notice if it got worse over time, or did it appear suddenly?

Thanks. It was gradual, becoming progressively worse over a few weeks. Initially, just a bit of hesitation, then the rough running became more pronounced. Before replacing parts, were your symptoms exactly the same? And did replacing the EGR valve resolve everything?

Yes, that sounds exactly like what I experienced. It started subtly and got progressively worse. All the symptoms you mentioned align with what I went through - the loud hissing, I forgot to mention that one. I'd say it's highly likely your EGR valve is the culprit, especially if it happened gradually. While I'm not a mechanic, I'd advise getting it checked by a professional. They can confirm the diagnosis and handle the replacement. Don't risk damaging the engine further by driving it like that, especially with potential emissions problems. A garage visit seems appropriate now.

Appreciated! It seems my hunch was accurate. The workshop confirmed the EGR valve was defective and jammed. I authorized the replacement and the car is now running smoothly. The repair cost me 355€. Thanks for sharing your experience; it gave me the confidence to pursue the repair!