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Understanding crankshaft position sensor


The crankshaft and camshaft position sensors, which are the most significant sensors in any engine, are critical to the distributor’s and ignition timing’s performance. The crankshaft position sensor is a multipurpose sensor that controls ignition timing, detects RPM, and calculates relative engine speed. Manual distributor timing is no longer necessary thanks to this sensor. To synchronize the fuel injector and coil firing sequence, the camshaft position sensor is employed to detect which cylinder is firing.

In today’s article, you’ll learn the definition, functions, diagram, types, working, and common symptoms of a crankshaft position sensor.

What is a crankshaft position sensor?

Crank sensors are electronic devices that monitor the position or rotational speed of the crankshaft in internal combustion engines, both gasoline, and diesel. Engine management systems employ this data to adjust the timing of fuel injection and other engine characteristics. The distributor had to be manually set to a timing mark on petrol engines until electronic crank sensors were available.

The crank sensor can be used in conjunction with a camshaft position sensor to monitor the engine’s piston-valve relationship, which is especially significant in engines with variable valve timing. This procedure is also used to “synchronize” a four-stroke engine when it first starts, allowing the management system to determine when to inject gasoline. It is also widely used to determine engine speed in revolutions per minute. The main crank pulley, the flywheel, the camshaft, and the crankshaft itself are all common attachment points. This sensor, together with the camshaft position sensor, is one of the two most critical sensors in modern engines.

Because the crank sensor position signal is used to time the fuel injection (diesel engines) or spark ignition (petrol engines), a failed sensor will cause the engine to not start or cut out while running. This sensor also provides speed information to the engine speed indicator.


The followings are the functions of crankshaft position sensors:

  • The crankshaft position sensor’s primary function is to determine the crank’s position and/or rotational speed (RPM).
  • The information sent by the sensor is used by Engine Adjust Units to control factors such as ignition timing and fuel injection timing.
  •  In diesel engines, the sensor will control the fuel injection.
  • The sensor output may also be linked to other sensor data, such as the cam position, to determine the current combustion cycle, which is critical for a four-stroke engine’s beginning.

The primary functions of a crankshaft position sensor include:


A powerful magnet can be found next to the crankshaft if you look closely. Around the crankshaft, you’ll also notice steel pins or pegs positioned at regular intervals. This magnet emits a continuous magnetic field all of the time. The steel pins around the crankshaft rotate around this field as the engine starts and the crankshaft spins. As a result of the variation in the field, an AC (alternating current) signal is produced. This also instructs the engine management unit (engine computer) to determine the rotational speed. As a result, the EMU can compute the camshaft’s position and speed in order to improve fuel injection and ignition.


We must learn one thing from modern automobiles. Only if the internal parts are moving at a specific required pace will the engines provide us with efficient performance. The onboard computer can only use the information sent to it by the crankshaft position sensor once it detects the rotation of the crankshaft inside the engine. This is when the computer makes little adjustments or fine-tunes to the engine in order to improve its efficiency.