Restore proper timing to your engine with this new direct replacement Crankshaft Position Sensor the CPS is a key component to your engine's timing and firing system. The Crank Sensor in most vehicles usually uses a magnet to determine the position of the crankshaft and sends the info to the Electronic Control Module (ECM) letting the computer know the position of the engine. A bad or malfunctioning crank sensor will often cause a service engine light error code and or cause a no start condition or rough running due to inaccurate ignition and fuel timing.