I bought our 2013 Sonata GLS used from a dealer in January of this year, a prior rental unit with 36k on it. We absolutely love the car and have managed to put over 8,000 miles on it in less than 4 months. Its fun to drive and has been mostly issue-free so far. However, in the past month or so, we've noticed an odd and intermittent (but apparently fairly common) buzzing / humming sound coming from the rear of the vehicle when at idle or very low rpm. Its sporadic, don't hear it all the time but it seems to be becoming more frequent. Its not the same familiar and normal fuel pump priming buzz when you first turn the key, I know that sound is normal. This is a low-volume humming noise that is DEFINITELY from the rear of the car, it can be heard inside the cabin but also audible from outside the car and it seems to be coming from underneath, possibly from the muffler or exhaust system. We can't hear it while driving, probably due to engine and road noise. But sitting idling or at a slow crawl its definitely noticeable. I did a Google search of the issue and discovered that many Sonata owners have complained of the same issue and have had their cars in to dealers to be checked out, but there is no sure determination as to whats causing the issue. Possibilities have ranged from the fuel pump to the exhaust system to the rear window defroster but that I can find, nothing for sure. Many of the complaints go back to 2011 models so its not a new issue for the 2013, it seems to be an issue with all years from 2011 to 2014. There has GOT to be a solution for this by now! Anyone have any ideas? I believe its something in the exhaust, it just makes sense and is located exactly in that area. Some have said they've had the fuel pump replaced (I don't believe its the pump, the sound and behavior just isn't quite right) and yet the problem returned almost immediately. Any help would be great. Thanks!

 

Hi. Im having the same issue with my sonata 2012. It's been few month having the problem and its exactly as what you mentioned. I always hear the noise when start the engine or accelerate from 0-30km/h. Did anyone manage to get the solution? Is it costly to fix it?

 

I heard it could a be a loose heat shield or washer within the heat shield. But I hear an odd squeak right before accelerating 🤦🏻‍♂️