Some vent solenoid.
It's the Evap canister vent solenoid, and the stupid ufcking "filter" Nissan put on.
It's not a hard fix, I can walk you right on through it if you need. What code do you have?
You just need a 4' piece of 1/2" gas hose and this filter:
https://www.amazon.com/Uni-Filter-UP-123-Push-Breather/dp/B000OO2Q2W