4 Runner SR5 2WD V6-3.4L (5VZ-FE) (1997)
Knock Sensor: Description and Operation
Knock sensors are fitted one to the right bank and left bank of the cylinder block to detect engine knocking. This sensor contains a piezoelectric
element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking
occurs, ignition timing is retarded to suppress it.