A capacitive sensor includes a first conductive structure; a second conductive structure movable relative to the first conductive structure in response to an external force acting thereon, wherein the first and the second conductive structures form a first capacitor having a first capacitance that changes with a change in a distance between the first conductive structure and second conductive structure, wherein the first capacitance is representative of the external force; and a diagnostic circuit configured to detect a first leakage current in the capacitive sensor by measuring an first electrical parameter that is affected by the first leakage current and comparing the measured first electrical parameter to a first predetermined error threshold, wherein the diagnostic circuit is further configured to generate a first error signal in response to the measured first electrical parameter being greater than the first predetermined error threshold.