Welcome. This code, P0446 is usually caused by a plugged EVAP solenoid. This solenoid has a filter in it that can get full of dirt and allow that dirt to flow to the canister which will block the air flow and set this code. The repair is to replace the solenoid with the updated valve and use 5/8 heater hose to relocate the filter portion to the underhood area away from the dirt. You will also need to clean the canister out. To do this, take it out, remove the hoses and use low pressure compressed air into the 2 smaller ports while tapping on the entire housing with a screw driver handle until the air is clean.