00 firebird 3.8 p0440

Alright people how are ya!.... good, now I just recently got a obd II code reader and it pulled a p0440. I now it has to do with either the gas cap all the way to the evap system. My question to you guys is......oh, and yes I'm changing the gas cap anyways even though I erase the code it still came up again so I'm assuming the cap needs replacing. Now, also let's say its the sensor or the purge valve or both, where are these located, again its a 3.8 manual firebird 2000. P.s. the car has almost 200,xxx mi. Still runs strong don't get me wrong except for that code. Again in advance thank you guys.

i would trace the lines to ensure that there are no leaks. if one is loose or cracked, the evap system may not have enough pressure and set the code.

but what lines exactly...I mean, I've done everything mechanik wise to this car myself. So I think I know a few thing, but this is something new since this has been a car that's lasted me this long and I plan to maybe squeeze a little more out of it. So, could you elaborate on what line or lines to check.