Intake Camshaft Position Sensor
The ECM identifies the cylinders from the combination of the intake camshaft position sensor signal and the crankshaft position sensor signal input into it.
This sensor signal is used for sensing a position of the intake camshaft. The sensor consists of a permanent magnet and Hall IC. When engine is running, the high and low parts of the teeth cause the gap with the sensor to change. The changing gap causes the magnetic field near the sensor to change. Due to the changing magnetic field, the voltage from the sensor changes.