a method for producing a filter element has three steps . in first step , a filter body including at least one first passageway and at least one second passageway or clearance extends closely and substantially parallel to the first passageway and communicate with first hole through a filter material is formed . in second step , a sheet - shaped thermoplastic adhesive is arranged on one end of the filter body , the first passageway and the second passageway or clearance are open at the one end of the filter body . in third step , the sheet - shaped thermoplastic adhesive is melted by heating to close and seal an end of the second passageway or clearance at the one end of the filter body so that the passageways do not deform .