Professional, premium aftermarket replacement Provides the performance and dependability you expect from ACDelco Manufactured to meet expectations for fit, form, and function An Professional, premium aftermarket Engine Crankshaft Position Sensor is the high quality replacement ideal for many vehicles on the road today. It monitors the position and rotational speed of the crankshaft. The signal from the crankshaft position sensor is used by the engine control module to determine fuel injection and ignition timing. This premium aftermarket replacement engine crankshaft position sensor is manufactured to meet your expectations for fit, form, and function.