I have worked on import cars for a living longer than I care to admit and the Evaporative emission code is the last code you want to see. The leak detection sounds off if it fails the test. The test is equivalent to .040' hole over ten minutes time or something like that. really hard to find. You can't see the leak, hear the leak, maybe smell it if lucky. I have chased gas caps as being the problem more than once so the first thing to do is that. Fixes it more than not, and anything more is really hard. If you don't use a factory cap that can cause the problem by itself. there is no reliable test for the cap.
Why they kill AWD I don't know. Subaru wipes out cruise control. I think they try to force you to fix it. I wouldn't be surprised the EPA might have required some more reason than just the light.
If you can fix the leak with JB weld, that might be all you need to do. I would try it. If it does cure it you have to reset the code, but any parts house has a reader and can do that. We reset and read for free here. Sometimes you want to see a code at least twice before diving right in and found it better to wait for the code to repeat.
Often the code reset requires two key cycles to return. The Cap may have preceded the rodent problem.