Crankshaft Position Sensor
An engine management sensor that monitors the rotational speed and position of the crankshaft to control fuel injection and ignition timing.
The crankshaft position (CKP) sensor is a vital electronic sensor used by the engine control module (ECM) to monitor the engine's primary rotating component. It measures the rotational speed (RPM) and exact position of the crankshaft, allowing the computer to determine which piston is moving up or down at any given moment.
The ECM uses the CKP sensor's signal to coordinate fuel injector spray timing and spark plug firing timing. In many modern engines, it works in tandem with a camshaft position sensor to manage variable valve timing. Without a signal from the crankshaft sensor, the engine computer cannot synchronize fuel and spark, and the engine will not run.
Crankshaft sensors operate in a harsh environment, subjected to extreme engine heat and vibration, which can cause internal wiring or electromagnetic coils to fail. Symptoms of a failing crankshaft sensor include engine stalling when warm, intermittent hard starting, a rough idle, engine misfires, and a check engine light. A complete sensor failure will cause the engine to crank but fail to start.
Replacing a crankshaft position sensor is a standard repair that restores signal communication. Since it is located low on the engine block near the flywheel or crankshaft pulley, it is sometimes difficult to access.