The knock sensor in the Pontiac Grand Prix sends a signal to the computer, which in turn signals the control module to adjust the timing when the sensor senses excess vibration or knocking in the engine. Knocking, often referred to as pinging or spark knock, happens when the fuel mixture is too lean, causing detonation. Depending on the year of the Grand Prix and its engine (a 3.1-, 3.4- or 3.8-liter engine), the sensor could have one or two wires.
Jack up the vehicle and support it with jack stands. Disconnect the knock sensor's wiring harness connector. The knock sensor is round. Just under the harness connector and above the round part, the sensor is hexagon-shaped so that you can grab it with a wrench.
Remove the sensor from the block with a wrench.
Screw the sensor into the block by hand as far as it will go. Tighten it firmly with a wrench. Plug in the wiring harness connector. Lower the vehicle off the jack stands with the floor jack.
