How to Fix a Knock Sensor

by Cayden Conor

All fuel-injected vehicles use at least one knock sensor. The knock sensor monitors excess vibrations in the engine then signals the computer. The computer uses the information from the knock sensor to make adjustments to the air and fuel ratio. If the knock sensor is malfunctioning, the computer cannot adjust for a rich or lean condition and, if not repaired, will cause internal engine damage. The knocking could be a slight pinging when you step on the gas, or it could be a loud, constant knocking sound -- almost like marbles rattling around in the engine.

Locate the knock sensor on your vehicle, typically on the front of the engine. It could be down near the side of the timing cover or, most likely, in the head -- the upper part of the engine.

Unplug the wiring harness connector from the knock sensor.

Slide a wrench onto the hexagon-shaped part of the knock sensor. Turn the knock sensor counterclockwise to unscrew it from the block or head. Remove the knock sensor and discard it.

Smear dielectric grease onto the threads of the new sensor. Screw the sensor in by hand as far as it will go. Tighten it firmly with the wrench. Plug in the wiring harness connector.

Items you will need

About the Author

Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.