The invention relates to a plug module (24, 124) for being received in an attachment component (10), which must be contacted at least electrically, particularly a fuel injector for installation in the cylinder head region of an internal combustion engine. Said engine is supplied with fuel via a fuel injection system, which has a low-pressure region. The plug module is a combined plug module (24, 124), which has a first plug part (26) for electrical contacting and a replaceable return component (38, 138) for a fluid to be removed from the attachment component (10).