A robust, low cost, compact and highly accurate rotary position sensor is disclosed for measuring the relative angular position (within a range ≦180°) of a housing or stator and a rotor. The housing carries a galvanomagnetic sensing element and is adapted for fixation to a relatively fixed portion of a host system. The rotor carrying a magnet is disposed for rotation about a fixed axis with respect to the stator and is interconnected to a relatively moving portion of the host system through intermediate linkage. The magnet is juxtaposed in substantially axial alignment with the galvanomagnetic sensing element for magnetic interaction therewith. The housing defines a cavity to receive potting material for encasing the galvanomagnetic sensing element and an adjacent buffer cavity interconnected by a weir, which diverts ant excess potting material into the buffer cavity.