Knock Sensor: Description and Operation

^ The turbocharging system uses a knock sensor and knock control unit to control engine knock (detonation) at higher boost pressures.
^ The knock sensor, installed in right rear side of engine block, detects knocking and sends a signal to the knock control unit. The unit in turn signals the ECU that knock is occuring.
^ The ECU regulates boost pressure through its control of the wastegate solenoid valve. When knock occurs, the ECU energizes the solenoid valve to open the turbo wastegate and lower boost pressure until knock is eliminated.
^ To further control knock, ECU controlled Electronic Spark Advance (ESA) Control System retards ignition timing 6° when the ECU receives a knock signal.
^ System includes a warning buzzer to indicate possible faults with wastegate, actuator or wastegate solenoid valve. Check these components if buzzer sounds.