Abstract: An accelerometric sensor for measuring pinking in an internal combustion engine. The sensor includes a base in the form of a sleeve with a flange extending therefrom and supporting at least one stacked piezoelectric ring, connecting disks and a seismic weight. The underside of the base is used as a contact surface between the sensor and the part to be measured. The underside has a central recess such that the average load distribution diameter over the contract surface is no smaller than the average of the shoulder. This shape may be achieved with a recess which is coaxial with the sleeve and which has a diameter greater than the external diameter thereof. The shape may alternatively be achieved by forming the underside in a concave shape.