I have remodeled a portion of my garage into a closet and a shower as part an adjacent new bedroom. I have an attic space above the remodeled area. Is there a requirement to build a fire wall to separate the attic above the new closet and shower from the rest of the garage attic? Thanks for any help on this!

You need to separate the closet/bath attic space from the garage. You can frame a wall from the top of the closet/bath wall up to the garage ceiling and drywall it. If you want to use the top of the closet/bath areas for storage, after you build the wall, make a door out of 3/4 ply and install a piece of drywall on it, garage side.
Or when you drywall the garage side framing of the closet/bath a make sure the open ends of the ceiling joists are covered over by drywall. Put a piece of 3/4 plywood on top of the closet /bath ceiling joists. Either way should pass code.

Thanks for the quick response!