Circuit Description

Knock sensor cannot differentiate between spark knock and other similar engine noises. When knock sensor cannot eliminate noise by retarding spark timing, DTC will set. The knock circuit is continuously monitored for these parameters.

DTC will set if PCM cannot reduce spark knock (as seen by knock sensor) by retarding timing. Knock sensor activity is probably due to engine noise and not spark knock. This diagnostic is run with engine running and cylinder in combustion event window.