Geared motor for a motor-vehicle wiping system comprising: - an electric motor including: - a rotor including magnetic elements, - a stator having the electromagnetic excitation windings of the rotor, - a rotary shaft rigidly connected to the rotor, - a reduction gear linking the rotary shaft and an output shaft of the geared motor, - a casing forming a protective envelope for said reduction gear, or the electric motor , and in which said reduction gear includes a worm screw and worm wheel gear, the worm screw being rigidly connected to the rotary shaft of the rotor , the worm wheel being rigidly connected to an output shaft of the geared motor, - bearing means for guiding the rotary shaft of the rotor in rotation in relation to the casing , a determination device for determining the angular position of the rotor including a multi-pole magnet that is rigidly connected to the rotary shaft of the rotor , [characterized in that] and in which the geared motor includes a heat sink attached to the multi-pole magnet and made of a different material from the multi-pole magnet , in the form of an element projecting radially from the rotary shaft and laterally from the multi-pole magnet towards said worm screw , that is distinct from the bearing means and the multi-pole magnet , said heat sink being in an intermediate position between said multi-pole magnet and the worm screw , arranged in the vicinity of the worm screw on said rotary shaft, including an internal bush for assembly of the rotary shaft , said element being designed to form a heat-exchange surface with the internal atmosphere of the casing , the distance Δ separating said heat sink from the worm wheel being equal to or less than the distance separating said multi-pole magnet from the worm wheel . - an electric motor including: - a rotor including magnetic elements, - a stator having the electromagnetic excitation windings of the rotor, - a rotary shaft rigidly connected to the rotor, - a rotor including magnetic elements, - a stator having the electromagnetic excitation windings of the rotor, - a rotary shaft rigidly connected to the rotor, - a reduction gear linking the rotary shaft and an output shaft of the geared motor, - a casing forming a protective envelope for said reduction gear, or the electric motor , and in which said reduction gear includes a worm screw and worm wheel gear, the worm screw being rigidly connected to the rotary shaft of the rotor , the worm wheel being rigidly connected to an output shaft of the geared motor, - bearing means for guiding the rotary shaft of the rotor in rotation in relation to the casing , a determination device for determining the angular position of the rotor including a multi-pole magnet that is rigidly connected to the rotary shaft of the rotor , [characterized in that] and in which the geared motor includes a heat sink attached to the multi-pole magnet and made of a different material from the multi-pole magnet , in the form of an element projecting radially from the rotary shaft and laterally from the multi-pole magnet towards said worm screw , that is distinct from the bearing means and the multi-pole magnet , said heat sink being in an intermediate position between said multi-pole magnet and the worm screw , arranged in the vicinity of the worm screw on said rotary shaft, including an internal bush for assembly of the rotary shaft , said element being designed to form a heat-exchange surface with the internal atmosphere of the casing , the distance Δ separating said heat sink from the worm wheel being equal to or less than the distance separating said multi-pole magnet from the worm wheel . <EOS>