Camshaft Position (CMP) Sensor (G20)

CMP sensor, located in distributor housing, monitors engine speed and piston position. CMP sensor has a disc containing 2 rings of slits; an outer ring of slits, each one a degree apart, and an inner ring of slits, each 90 degrees apart. An LED light and photodiode (for each set of slits) create a pulsating voltage when LED light is broken. The outer ring is used to determine engine speed, while the inner ring determines No. 1 cylinder TDC position for injector and ignition timing.