Hey there! Actually, something similar happened to my 2012 Hyundai Sonata not too long ago. That check engine light, the power slump, odd noise... sounded like a bad concert, right? Well, turns out it was deposits in the combustion chamber causing all the trouble. I had to take my ride to the garage (again *rolls eyes*) and they did a pretty comprehensive engine clean-up. They removed all the crud blocking up the works, which essentially is carbon deposits causing the cylinder knock you talked about. The clean-up process wasn't all that simple, but the mechanic knew his beans. We're talking removal of spark plugs and injectors, and some intake cleaning. Fun day at the garage, I tell you. In layman's terms, the mess in the combustion chamber throws the engine's timing off, causing those symptoms you're seeing. It was a pretty serious issue for me too, so don't ignore that light. Also, this might seem obvious but if you haven't changed your oil in a while, do that ASAP - good oil quality can help combat the deposit issue. Hate to say it but you might have to bite the bullet and take your Elantra in for a check-up. Don't skimp on some pro help, yeah? Good luck!

Hey! Appreciate the detailed heads-up. Sounds like quite the ordeal with the Sonata. Seems like this little engine light might be more than just a problem. I've got to tell you I'm not looking forward to reuniting with my mechanic after our last rendezvous. But, I guess needs must, and all that. Listen, if it's no bother, I was wondering if you can recall how much you had to shell out for that comprehensive engine clean-up? Just trying to get an idea of what I might be up against. Also, I hate to sound paranoid but ever since your engine clean-up, have any other issues crept up? Thanks again!

Hey there! Ah, the dreaded mechanic reunion - I feel your pain. As for the cost, I shelled out around 425 Euro - a bit of a hit to the wallet for sure, but trust me, it was worth every penny. That gunk in the combustion chamber was gunning for my Sonata's engine, so clearing it up was critical. After the cleanup, the knocking combustion in the cylinder was fixed and, honestly, the car's been smooth sailing ever since. No other issues crept up, knock on wood. Seems like my mechanic really got his act together this time around - the old girl hasn't run this well in ages. I reckon your Elantra might need the same treatment, but don't panic just yet. It'll all come down to the exact diagnosis. Remember, a little TLC now could save you from a heap more trouble (and cost) down the line. Good luck!

Hey! Thanks so much for pitching in. No kidding about the TLC, and this might just be the wake-up call I needed. 425 Euro, eh? It's a bitter pill to swallow, but guess there's no point penny-pinching when it comes to the old banger's health. Thanks for sharing your Sonata journey too. Honestly, my Elantra hearing it might perk her up. She's probably feeling a bit neglected, the poor thing. On that note, off to make the mechanic appointment. Fingers crossed he's got his act together like your guy. Will keep you lot posted. Cheers for the help!