Bad Crank Position Sensor Symptoms

by Quinn MarshallUpdated July 26, 2023

The crank position sensor, sometimes referred to as the crankshaft position sensor or crank sensor, is a small plug found that is part of the engine management system in a piston engine. It monitors the rotational speed and position of the crankshaft. This information is relayed through an automotive computer, which then uses it to calculate ignition timing. A faulty crankshaft position sensor could be caused by bad construction or high mileage on the vehicle.

Crankshaft sensor problems could lead to an engine failure or misfire, a worse fuel economy and even issues with your fuel injectors depending on if your car takes gas or diesel. In order to do some troubleshooting, here are some symptoms of a bad crankshaft position sensor.

No Ignition

If a crankshaft position sensor goes bad, no signal will be transmitted to the PCM (Powertrain Control Module) also known as the ECM (the Engine Control Module) or Engine Control Unit (ECU), which will result in a failure to start. The CKP can be checked by a mechanic with a special scan tool that will test the sensor to see if it is responsible for the problem. If it’s not, it’s likely an engine performance issue.

Car’s Engine Stalling

If the crank position sensor is going bad but still functional at times, the vehicle’s engine may start normally but then rough idle on other occasions. It could also be hard starting the car, or you may feel more intense engine vibrations when you start the car. In some cases, you could have an engine misfire. The vehicle may start and run fine, but then shut down without warning while driving.

Reduced Fuel Economy

If you have a failing crankshaft position sensor, then you might notice that you need to fill up on gas more. That’s because your fuel injection system isn’t sending gas to your engine correctly. If this is your only symptom, be sure to get your vehicle checked by a mechanic; there could be other issues within the ignition system or other parts of the car.

Check engine light

An illuminated check engine light can mean many things, but it’s also one of the most common symptoms of a bad crankshaft position sensor. If the crankshaft position sensor is going out, the check engine light may come on. Depending on the vehicle, a bad crank position sensor could also result in warning lights or trouble codes near the tachometer when the key is turned to the on position three times.

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