A throttle body assembly includes a housing defining a throttle bore with a throttle plate in the bore and mounted on a shaft. An electric motor has a pinion gear. A gear assembly includes an intermediate gear and a sector gear and transfers rotational drive from the electric motor to the throttle plate. Biasing structure biases the sector gear and thus the shaft to cause the throttle plate to close the throttle bore defining a closed position thereof. When the motor is energized, rotation of the pinion gear causes rotation of the gear assembly, against the bias on the sector gear, thereby causing rotation of the shaft to move the throttle plate from the closed position to an open position. A position sensor assembly determines a position of the plate.