A control system of at least one flap of a fluid duct of an intake system of an internal combustion engine, including: a swivel axis, at least one flap connected off-center to the swivel axis by which the at least one flap can be swiveled within the fluid duct between positions with different degrees of opening, a swivel lever connected to the swivel axis, the swivel lever pivoting the swivel axis, an elastic working return element connected directly or indirectly to the swivel lever and applying a force to the at least one flap to return the at least one flap toward a home position.