Crankshaft Position Sensor: Function, Failure Symptoms, and Replacement cost

In this post, we will discuss about one of the important sensor in the engine systems called “crankshaft position sensor”. Read the full article below to understand basic function, working principle, failure symptoms and replacement cost of this sensor.

Basic Function and Working Principle

The internal combustion engine depends on the crankshaft for its rotational energy. The main function of the crankshaft is to convert reciprocating energy (also known as linear energy) into rotational energy. The latter will then give power to the wheels of the drivetrain below the car. This is how the wheels can spin forward and allow the vehicle to move in that direction.
As for the crankshaft position sensor, this simply detects how fast the crankshaft is spinning. Once it detects the spinning rate, it sends this information to the engine control unit of the vehicle. This information will determine how the engine control unit regulates the timing of the fuel injection system and ignition system. You need the timing to be just right for the engine to produce the proper amount of power.

The crankshaft position tells the engine control unit all it needs to know. You see, the crankshaft uses a timing chain, gearwheels, and a belt with teeth to drive the camshaft. The engine depends on the camshaft to operate the exhaust valves at the appropriate times. If they don’t open and close correctly, it creates problems with the exhaust system. This all links back to the functionality of the crankshaft.

Therefore, the engine control unit will know the position of the crankshaft through the crankshaft position sensor. By judging the speed of the crankshaft in conjunction with its position, it will know the status of the camshaft’s functionality too.

Top 6 Bad Symptoms

An internal combustion engine must have a functional crankshaft position sensor. Otherwise, the engine control unit won’t receive accurate information about the position and speed of the crankshaft. This will cause all sorts of problems with the functionality of the engine and the car’s driving performance. You will surely recognize these symptoms as they become present.

Below are the top 6 symptoms of a bad crankshaft position sensor.

1) Engine Vibrations – Are there vibrations coming from your engine? When you have a bad crankshaft position sensor, that means the engine control unit cannot manage the crankshaft properly. As a result of this, your engine will vibrate quite extensively. You may even feel these vibrations sinking into the steering wheel as you hold it with your hands.

2) Check Engine Light – The engine control unit stays in constant communication with the crankshaft position sensor. If there is ever something wrong with the sensor, then the computer will receive improper information regarding the speed of the crankshaft and its position. This will cause functionality problems with the engine, resulting in the Check Engine warning light activating on the dashboard. In fact, this should be one of the first symptoms of a bad crankshaft position sensor.

3) Weak Engine Performance – With a bad crankshaft position sensor, your engine control unit won’t know the correct position of the crankshaft or cylinders. This will cause a delay in the control unit’s ability to sustain the operation and performance of the engine. During this delay, there will be moments of hesitation each time you step on the gas pedal a little bit harder. Sometimes it won’t respond at all. This can be very dangerous on a road that requires you to go faster without hesitation.

4) Trouble Starting Car – The engine control unit will be notified when the crankshaft position sensor is having problems. It is given a special malfunction code from the sensor which indicates there is some kind of problem with its functionality. When you attempt to start your vehicle as this trouble present, it will be more difficult to get the engine going. If the problem continues without being resolved, you may not be able to start your engine at all.

5) Engine Stalling – You may be driving along one day and have your engine suddenly stop running. This is engine stalling and it can happen quite frequently when you have a bad crankshaft position sensor. If you don’t replace this sensor soon, your engine will eventually stop working altogether. Then you will have no choice but to get your vehicle towed to a mechanic, so the sensor can be replaced.

6) Cylinder Misfiring – A crankshaft position sensor that fails will not be able to accurately transmit data regarding the piston position to the engine control unit. This often results in a misfire inside one or more of the chamber cylinders. Sometimes a bad spark plug can do this too but if you are experiencing any of these other symptoms, don’t rule out the possibility of a bad crankshaft position sensor.

Replacement Cost

If you experience at least two or more of these symptoms, then you probably have a bad crankshaft position sensor. The only way to know for sure is to bring your vehicle to a licensed mechanic and have them diagnose the problem for you. Once they have verified that it is the crankshaft position sensor causing the problem, then you can proceed to have the sensor replaced.

Read also: Oxygen Sensor: Basic Function, Failure Symptoms and Replacement Cost

The replacement cost of the crankshaft position sensor is anywhere from $120 to $300. The cost of the part itself will be around $75 to $120. The cost of the labor will be anywhere from $45 to $180. You need to factor in the estimated taxes and other fees that will be added to the total amount as well. In the end, this won’t be a terribly expensive replacement job to get done. It is worth the investment because you are protecting the functionality of your engine.

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