Ran into this on my daughter's 11 Sonata. Had it towed in on a Sunday, didn't get a loaner until Thursday when they looked at it. In my case it didn't ventilate the block, and while it was still a fairly easy diagnosis for me, they have to make it official. Also, at least in my case, our local Hyundai dealer is absolutely slammed all the time, so I gave them the benefit of the doubt as far as checking it out since I kind of dumped it in their laps when their schedule was already booked out.