Service function guideKnock Sensor Diagnosis

This guide provides a complete, professional procedure for diagnosing knock sensor faults and interpreting knock retard data on modern gasoline engines, written for working mechanics and serious DIYers who need a repeatable diagnostic path. It explains how the piezoelectric knock sensor and the engine control module (ECM) work together to detect detonation and pull timing, then walks through preparation, live-data capture, circuit testing, and sensor replacement verification. You will learn to distinguish a failed sensor from a wiring fault, a mechanical noise source, or a calibration problem, and you will finish with a documented result you can hand to the customer or use to confirm the repair.