Where is gasoline filter

Part of the fuel pump on this :-(. You might need to replace the fuel pump to replace it unless Hyundai/Kia will just sell you the filter and it's designed to be modular. You can also often use a aftermarket one on the OEM pumps if Kia won't sell it to you but if this is under the 5/10 year warranty, buy the fuel pump assembly if that's all you can buy. If this were older (think 10+ years) they are OOW and past warranty, so it's not a warranty risk.

Hyundai/Kia gatekeep their manuals so I can't find free ones for these without knowing if you have the right year, but it's under the rear seat or trunk area, you need to remove the fuel pump ring with a tool like this and then you can get to the fuel pump. Just make sure you wear eye protection (eyeglasses don't count here) and if you can pull the fuel relay to drain the fuel system so it's no longer under pressure I would do that - it does create DTCs, so buy a code scanner like this to clear it out once you are done. If there is no service port, you need to drop the tank. Try this P/N: 31112-B1000