Knocking is a phenomenon characterized by undesirable
vibration and noise and can cause engine damage. The two Knock Sensors
(KS) are installed inside the V-valley of the cylinder block and sense
engine knocking.
When knocking occurs, the vibration from the cylinder block is applied as pressure to the piezoelectric element.
When knocking occurs, the sensor produces voltage signal and
the ECM retards the ignition timing. If the knocking disappears after
retarding the ignition timing, the ECM will advance the ignition timing.
This sequential control can improve engine power, torque and fuel
economy.

Other information:
Components
1. Front muffler2. Center muffler3. Rear muffler4. Hanger5. Gasket
...
Replacement
1.
Remove the front seat belt upper anchor.
(Refer to Front Seat Belt - "Front Seat Belt Retractor")
2.
After loosening the mounting bolts, remove the height adjustor (A).
Tightening torque :
39.2 ~ 53.9 N.m (4.0 ~ 5.5kgf.m, 28.9 ~ 39.8 lb-ft)
3.
Install in the revers ...