Knock sensor for a 2003 chevy Z71 5.3 L

These sensors are quiet a problem. They are located under the intake and normally go off because the engine got washed sometimes the water will evaperate and the problem goes away but anymays the intakes gota come off there are 2 of them so i would recomend replacing both while ur at it

They are usually mounted in the passenger side of the block, in the middle of the side of the block just a head of the starter. This is what you are looking for:

Knock Sensor Operation: A sensor that signals the engine-control computer when detonation is detected, momentarily retarding ignition timing until detonation ceases.