Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Knock Sensor (KS) Operation




The knock sensor detects abnormal vibration (spark knocking) in the engine. The sensor is located on the engine block near the cylinders. The sensor produces an AC output voltage which increases with the severity of the knock. This signal voltage is input to the PCM. The PCM then adjusts the Ignition Control (IC) timing to reduce spark knock. DTC P0325 Knock Sensor (KS) Circuit DTC P0327 Knock Sensor (KS) Circuit are designed to diagnose the PCM, the knock sensor, and related wiring, so problems encountered with the KS system should set a DTC.

Refer to Knock Sensor (KS) System Description description of the knock sensor system.