Knock Sensor
WARNING: This page is about a different car, the 2003 Suzuki XL-7, 2003 Suzuki Vitara, 2003 Suzuki Grand Vitara, and 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
For testing procedures, see DTC P0327 and P0328 in appropriate SELF-DIAGNOSTICS article.