Knock Sensor (KS)
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Mazda Tribute, 2003 Mazda Protege5, 2003 Mazda Protege, 2003 Mazda MX-5 Miata, and 2003 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
The KS transmits a signal to the PCM which retards ignition timing when knocking occurs.