Will Valium cover up marijuana in a pee test?
No.
When testing for illegal substances they have a few options,
hair, blood, pee are the basics.
Marijuana will not be covered up by anything other that a lack
of marijuana, 45 days to get clean if you are a regular 3-5 days
for first couple of times.
But Valium will not cover it up, all that will do is add Valium
to the list of substances found in your body