What makes you think it is in fact a valve and not a leak in one of the hoses?
I know you said after some diagnostics, I just didn't know how far you have dug in.
The system goes from the fuel tank through fuel vapor vent valve to the EVAP canister through a line. Then with the vehicle on, the PCM signals the EVAP canister purge valve that you mentioned already to open up and vent the vapors into the engine intake manifold from the canister.
P0442 specifically is for a small leak in the actual EVAP system which can be as small as .04.
P0443 is for purge valve circuit malfunction.
P0455 is for a major leak in the system or no flow signaled.
P1443 is for small flow or or no purge flow detected.
P1450 is for excessive vacuum in the fuel tank.
P1451 is for canister vent solenoid malfunction.
All 4 of these are signaled by the PCM after testing the system which also monitors any high or low signal readings, correct EVAP operation, and uses positive and negative methods to test the system so I would say if it was just a bad valve, it wouldn't be registering as just a P0442 code. Also with the way the system works I think it is probably more likely that you have a leak in one of the lines, gas cap, fuel fill neck, canister vent solenoid loose from the canister, etc rather than a bad valve.
The EVAP canister purge valve is normally closed and is controlled via the PCM to let vapor into the intake manifold during engine operation with all of the vapors being stored inside of the EVAP canister so even if you had say a bad purge valve staying open all the time for some reason, and with the canister vent solenoid normally being open, you'd be pulling it directly into the intake manifold all the time which I feel like would be somewhat noticeable if it was always doing that. Not to mention if that was the case, you would probably have an P0443 code. Of course it is early in the morning and I work nights so I am kinda just thinking out loud here.
Do you have access to a smoke machine by chance and what type of diagnostic equipment do you have?
I can also give you the testing procedures for the canister purge valve but again I think you would definitely have an P0443 code if the valve went bad but crazier things have happened.
EDIT: might help clarify or better visualize what I was saying. I worked kinda hard on this, my brain is done for the night lol so time for me to sleep. I will check back in later today
