Mechanics

Crankshaft Angle Sensor CKS

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This article describes how an automotive crankshaft position sensor works.

This information pertains to all vehicles except electric cars. A crankshaft position sensor (CKS) is used to reference crankshaft rotation as the engine is running while supplying feedback data to the main computer. This sensor is mounted near the crankshaft, flywheel or in the engine block depending on manufacturer. As the crankshaft spins it creates an electrical pulse pattern that changes with engine speed. This wavelength controls computer output circuits such as fuel injector pulse width and timing adjustments. The timer reluctor wheel is fastened to the crankshaft which is used by the sensor.


Crankshaft Angle Sensor

This sensor goes by different names depending on the manufacturer, crankshaft angle sensor, CKS sensor, crankshaft position sensor but performs the same function. When these sensors fail they can cause intermitted stalling, no start and random misfires. Usually the sensor will start to work again once it has cooled. Some computer controlled systems may have a difficult time detecting a failing sensor because there are other reasons an engine can stop running such as stalling when the clutch is engaged to quickly. Information is compiled from both crankshaft and camshaft position sensors to output camshaft position adjustments performed by the variable camshaft timing actuator-phaser. A knock sensor is used to detect detonation-pinging to further input data for the computer while retarding ignition timing to compensate.

A crankshaft position sensor uses a magnetic coil mounted inside a plastic housing while supplying an electrical connector to transfer data to the computer. The computer also uses this sensor to gather misfire data due to the temporary slow down of the crankshaft while the misfire occurs. When the engine is being cranked over the computer uses the crankshaft positions sensor to confirm the engine is cranking over. Once this confirmation is received the computer will signal various relays and systems that the engine ready to start. When replacing a crankshaft position sensor always use an OEM (Original Equipment Manufacturer) part or equivalent, cheaper sensors do not not last as long or perform properly.

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-20)