GreetingsCustomerand welcome to JA! I will do my very best to assist you with your problem..
The P0446 is for the vent control valve under the car near the canister. It is stuck closed so when you are trying to fill the tank, there is no place for the fuel vapors to go. This makes the fuel come back up the fill tube and shut the pump off. Here is a picture of the location of the part. This is how you will resolve the issue is to replace the valve.
Hope this helps!