Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensor And Engine Speed Sensor:

The crankshaft position sensor (or reference sensor) is a magnetic induction type sensor located on the rear of the engine block. It contains a permanent magnet, and an iron core surrounded by an induction coil. The magnet sets up a magnetic field around the iron core. As the engine turns, a reference mark located on the flywheel passes in close proximity to the end of the iron core, disturbing the magnetic field. This change in the magnetic field induces a small current in the coil surrounding the iron core, creating a wave-like pulse that the ECU can detect. This pulse indicates the exact position of the crankshaft once each revolution, giving the ECU a reference from which to calculate the ignition timing.