A method to control an electric motor, which operates a pump to feed a water-based operating liquid in an injection feeding system for an internal combustion engine; wherein the electric motor comprises three stator windings and a rotor, which is provided with at least one permanent magnet; the control method comprises the steps of: supplying, during a normal operation to pump the water-based operating liquid, the three stator windings with three corresponding alternating electric currents (I 1,I 2,I 3), which are out of phase, so as to generate a rotary magnetic field, which drags the permanent magnet and, hence, causes the rotation of the rotor; and supplying, during a pre-heating procedure to pre-heat the pump before starting to pump the water-based operating liquid, the stator windings with a system of alternating electric currents (I 1,I 2), which does not determine any movement of the rotor and only generates heat through Joule effect in the stator windings; the control method is characterized in that it comprises the steps of: supplying, during the pre-heating procedure to pre-heat the pump before starting to pump the water-based operating liquid, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding; and supplying, when the electric motor is turned off for an extended stop after a turning-off of the internal combustion engine and namely when the injection feeding system switches to a parking condition, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding, so as to put the rotor in a fixed and predetermined parking position. supplying, during a normal operation to pump the water-based operating liquid, the three stator windings with three corresponding alternating electric currents (I 1,I 2,I 3), which are out of phase, so as to generate a rotary magnetic field, which drags the permanent magnet and, hence, causes the rotation of the rotor; and supplying, during a pre-heating procedure to pre-heat the pump before starting to pump the water-based operating liquid, the stator windings with a system of alternating electric currents (I 1,I 2), which does not determine any movement of the rotor and only generates heat through Joule effect in the stator windings; the control method is characterized in that it comprises the steps of: supplying, during the pre-heating procedure to pre-heat the pump before starting to pump the water-based operating liquid, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding; and supplying, when the electric motor is turned off for an extended stop after a turning-off of the internal combustion engine and namely when the injection feeding system switches to a parking condition, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding, so as to put the rotor in a fixed and predetermined parking position. supplying, during the pre-heating procedure to pre-heat the pump before starting to pump the water-based operating liquid, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding; and supplying, when the electric motor is turned off for an extended stop after a turning-off of the internal combustion engine and namely when the injection feeding system switches to a parking condition, two sole stator windings with two corresponding alternating electric currents (I 1,I 2), which are in phase with one another and, adding to one another, return through a third stator winding, so as to put the rotor in a fixed and predetermined parking position.