Filter system for the filtration of fluid

Filter system (10) for filtering fluid with an at least two-part reveal filter housing having an inlet (24) for fluid to be filtered and an outlet (22) for filtered fluid and being provided with a filter element (16) which is arranged in the filter housing in such a way in that the inlet (24) sealingly from the outlet (22) is separated, characterized in that an activation / deactivation device (432) is provided which is a configured as a source fluid passage (122) of the filter housing with built-in filter element (16) for preventing a signal directly or indirectly selectively automatically opens, closes or keeps closed.