Does uv dye help in determining cover valve gasket leak?

It's oily directly below the valve cover? For starters you could just wipe it all clean, then monitor closely, for fresh leakage.

How many miles on it? You're first owner?

Was the code you posted previously resolved?

 

What exactly are you trying to learn ?
If you already know that it is leaking at the valve cover gasket.......that's pretty much all you need to know.

Some vehicles can have really minor seepage there and go for years with no noticeable increase in oil consumption.