The knock sensor on the 2002 GMC Sierra 5.3-liter engine is located on the lower side of the engine block, just below the exhaust manifold, on the passenger side of the engine. It senses pre-ignition knock (pinging), then alerts the computer (ECM) to institute a change in the ignition timing. If the knock sensor is not working, it will not allow the computer to change the ignition timing when needed, and may cause additional internal damage to the engine.
Tools Used: Tools, Set of sockets, Extension
Replace Knock Sensor
Disconnect the battery ground cable and lay it aside, ensuring that it does not touch metal. Unplug the wiring harness connector on the knock sensor by pulling the tabs on the side of the plug out, then pulling the plug out of the sensor. Unbolt the sensor from the block using the appropriate sockets. You may need an extension if the socket doesn’t quite reach the bolts. Bolt the new knock sensor on the side of the block and tighten the bolts firmly. Plug the wiring harness connector into the sensor. Reconnect the battery ground cable.