What Is a Cam Shaft POS Sensor?

Updated February 21, 2017

A camshaft refers to a shaft that connects to a cam, or rotating piece of linkage designed to transform linear motion into rotary, or rotational motion. A camshaft position can be determined via a camshaft POS sensor.

Camshaft Sensor

A camshaft POS, or position sensor, sends an electronic signal to the engine control unit (ECU) to inform it of the camshaft's current position. This enables the engine control unit to control fuel injection and ignition timing.


The camshaft position sensor typically operates via a magnet mounted in the rotating disc, which creates a magnetic field when current is applied. A Hall effect sensor can also be used, which refers to the effect caused by the production of a difference in voltage, known as Hall voltage, as it flows across an electrical conductor and a magnetic field perpendicular to the current.

Crankshaft Position

In engines using sequential fuel injection or distributor-less ignition systems, the camshaft position sensor also signals the ECU about the relative position of the crankshaft. The ECU uses the position of the crankshaft along with the camshaft to establish which cylinder is firing in the engine, in turn facilitating the ECU's ability to match the cylinder firing order with the fuel injection order.

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