I have a 2001 Galant ES 4 cyl. I have code P0455 Large Leak Detected.

To eliminate it being a gas cap problem, I erased the code and tightly rubber banded the gas tank inlet with a plastic bag to get a tight seal. But P0455 code eventually came back.

I would like to trouble shoot the other components but looking for a leak in all the hoses, and maybe replacing some parts. But I am unfamiliar with what to look for and the location on my galant.

Does any one have any information and pics on how I can find and identify the emmission components to troubleshoot this problem?

Thank you.