The crankshaft position sensor is an electrical component in vehicles that tells the system's onboard computer where the crankshaft is currently located. This information allows the system to adjust fuel flow to individual pistons and ensure smooth rotation, even at higher RPMs.
Crankshaft position sensors replace the distributors commonly found in older vehicles, helping the engine gauge and maintain the correct timing without interfering with the positioning of the crankshaft during regular operation. There are four different major types of crankshaft position sensors, but all four fulfill the same purpose in the engine. The crankshaft position sensor works with the onboard computer's ECM system to ensure proper fuel delivery as the vehicle runs. The crankshaft position sensor typically lies near the crankshaft pulley or flywheel, and it may appear on the front or rear of the engine.
Crankshaft position sensors may fail over time. Since they are electrical components, fluid buildup in the system or external contaminants, such as rainwater, can damage sensors during regular vehicle operation. Signs that a crankshaft position sensor is failing include a check-engine light message, engine stall or slowdown, and rough idling or backfiring. These symptoms may indicate that replacement or repair is necessary for continued vehicle operation, and some vehicles may not start at all until this component functions normally again.