A plug-in sensor for measuring at least one property of a fluid medium, in particular for use in the coolant circuit of an air conditioning system of a motor vehicle. The plug-in sensor has at least one sensor for detecting the at least one property. Furthermore, the plug-in sensor has at least one sensor body having an external thread for threading the plug-in sensor into a threaded bore hole of a housing. Furthermore, the plug-in sensor includes a sealing surface for sealing an inner space of the housing against an outer space. The external thread has at least two threaded sections: a first threaded section including at least one continuous thread, and a second threaded section including at least one interrupted thread, at least one interruption of the at least one interrupted thread forming at least one blow-out groove.