Abstract: A variable reluctance sensor including a close-ended hollow housing which contains and thereby protects the operative components of the sensor. The sensor includes a bobbin portion interconnected with a connector member attachable to a submersible connector. An elongated pole piece extends through a bore in the bobbin barrel and press fits into a cavity in the connector member. A magnet is disposed at the end of the pole piece, and a magnet wire coil is wound around the bobbin barrel and electrically connected with conductors in the connector member. An outer hollow housing, which surrounds the bobbin portion, includes an open end portion which is ultrasonically welded to the connector member. After ultrasonic assembly of the housing to the connector member, the magnet rests against the opposite, close-ended portion of the housing. In an alternative embodiment, the housing and bobbin portion may be keyed to ensure proper assembly, and further a leaded sensor may be provided.