Abstract: A sensor has a magnetic circuit and an electric circuit for scanning the passage of magnetizable and non-magnetizable material of relatively movable parts. The sensor has a housing made of first and second parts which define an interface between them. The first part of the housing can be mounted to a cylinder wall and includes a portion of a magnetic core. A remaining portion of the magnetic core is embedded in the second housing part and an electric circuit operatively coupled with the magnetic core is mounted entirely in the second housing part so that the interface between the housing parts is free of electrical contacts to thereby prevent signal degradation due to contamination of electrical contacts.