July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!
Knock Sensor
WARNING: This page is about a different car, the 2009 Honda S2000, 2008 Honda S2000, 2007 Honda S2000, and 2006 Honda S2000. However, it is still accessible from the selected car via links, so may be relevant.
The knock control system adjusts the ignition timing to minimize knock, using signals from the knock sensor.