The knock sensor on a Chevy 2.4-liter engine is located near the rear of the engine, under the exhaust manifold. It is mounted in the engine block, near the top of the cylinder, so that it can sense any excess vibration in the engine. When the knock sensor senses vibration, it sends a voltage signal to the computer. The computer uses the signal to adjust the air-to-fuel mixture going into the engine, so that any pinging and knocking is reduced. If the knock sensor is not replaced when it malfunctions, it will cause engine damage.
Remove the negative battery cable and set it aside, ensuring that it does not touch metal.