US Patent 7769536 Diagnostic systems and methods for engine knock sensors

An engine control system includes a digital signal processing (DSP) module that generates a fast Fourier transform (FFT) of an engine knock signal generated by an engine knock sensor. An intensity determination module determines an engine knock intensity based on one of a maximum of and an average of the FFT. A status determination module determines a status of the engine knock sensor based on the engine knock intensity, a plurality of predetermined knock intensity thresholds, and a rotational speed of an engine crankshaft.