Ran in to this issue that other members may be interested in. I found out that there are two sizes of cabin air filters for the 2009 Sonata cabin air filter depending on your VIN No. so when you go to your local auto parts store be wary. The genuine part numbers from Hyundai are 08790 2G000A and 08790 3K000A. The 3K one is smaller and does not sit on the shelf correctly.