How to fix p0456 code for Hyundai Santa Fe?

So, I have my engine light on for couple of years now and the code is P0456. I tried some of the fix that can be found in youtube like tightening the gas cap or replacing the gas cap but it didn't fix the error code. Is there another way to fix this other than going to a mechanic? I can smell gasoline inside my vehicle after refueling, not sure if this is related to the problem.