If a 2012 Prius has a timing cover leak, what should be done?

When the timing cover on a 2012 Toyota Prius has a leak, it comes from primarily one of two locations. More than likely, You'll have a leak coming from the timing cover gasket. Alternatively, it's possible that there's a small crack in the timing cover itself. If Your timing cover is cracked, this necessitates a total replacement of the component. However, if You have a leak from the timing cover gasket, You may be able to repair the leak if it is small enough. Some good aircraft grade gasket maker can occasionally plug a leak; however, if You're trying to be thorough (or if the leak comes from a damaged area of gasket more than a millimeter or two in size), You'll need to have the entire gasket replaced.