could be any number of leaks in the vapor recovery system. the canister is under the car in the rear, by the gas tank. but there are lines going back to engine too that could be damaged. or some of the lines in the engine bay. i know theres one that always rubs if you have aftermarket intake and eats a hole eventually. check that. also try getting a new gas cap, over time the pressure mechanism inside wears out, so does the o-ring seal.
Man, I had a terrible problem with that code. Lucky for me it was an easy fix, other people, not so easy.
If you had recently installed an intake, you may have disconnected the EVAP Canister Purge Valve, the one near your IAC sensor. Took me 2 long months just to figure that one out. Code was gone afterwards.
If that's not the case, apparently if you live in an area where winter comes by, the salt from the plowing/salt trucks end up corroding the solenoids and/or the 2-way valve and/or the vent shut valve, causing a blockage of the EVAP system. I don't know if we have a PCM in our cars, but in other cars it would cause it to short out.
In terms of the testing, I'm pretty sure you gotta take it to Honda for that. I know it requires some machine but I forget which one.
im thinkning that that the solenoids are not opening as well, i have been listening to the tank when i take the cap off. every time that i take it off there is alot of air coming out of the tank, making me believe that the fumes are not getting to the canister...?