Knock Sensor: Description and Operation

NOTE: Check underhood label, or Application Charts for vehicle emission control equipment.

ESC--used in conjunction with Electronic Spark Timing (EST)--reduces spark advance during periods of detonation.
- "Knock" or "Detonation" sensor--mounted in the engine block or intake manifold--signals the ESC controller when detonation occurs.
- ESC Controller signals the ECM which reduces spark advance.
- When detonation ceases and the ESC controller is no longer receiving knock signals, spark control reverts back to EST.