EVAP leak, code P0440 and check engine light is on

Hello, unfortunately these newer systems are so expensive. I wouldn't have the filler neck replaced until the leak is found. It could be the charcoal canister, the vent valve, a line, etc. You can try a black light, some systems have dye in the Freon with and oil for finding leaks. What I use is a smoke machine, you can get them on eBay for cheap and they're great for finding leaks around the intake manifold, coolant system, EVAP system, exhaust leaks, etc. After you find the leak make sure to erase the code, sometimes a diagnostic code will shut a system down. Here's one of 2CarPros repair articles. If you have any more questions, don't hesitate to ask. You're going to have to find the leak though.

https://www.2carpros.com/articles/evap-system-code-repair