The invention relates to a device for producing a sealed electrical connection through an engine block crankcase wall in order to connect a sensor or actuating unit contained in the engine block to a central unit comprising a connector provided with at least one bore, which is intended to be arranged in an opening of said wall, at least one electrical contact connected to a wiring harness, said electric contact being surrounded by at least one O-ring seal and arranged in the bore of the connector, said device also comprising an over-moulded part on the wiring harness, an end of the electrical contact connected to the wiring harness and an end of the connector, such that, after the device has been mounted in the opening, the junction between said over-moulded part and the connector is situated on one side of the wall.