How to check if crankshaft position sensor is bad

When it comes to the proper operation of your vehicle's engine, one key component is the crankshaft position sensor. It keeps track of the location and rotational speed of your car's crankshaft.

It also sends the data to the motor control unit in order to make proper adjustments in relation to operating conditions. If your crank sensor isn't working right, you'll have a problem on your hands.

In fact, many modern engines simply won't operate at all if the crankshaft position sensor fails to provide a correct signal.

What follows is a look at 5 signs signaling that your crank sensor might be going kaput.

1. Crank Sensor Problems Could Make it Hard to Start Car

One sign that your crankshaft sensor might be failing is if you find it hard to start your vehicle. The sensor keeps track of the speed and location of the crankshaft. If it's failing, your vehicle might be difficult to start up.

In fact, the problem might be an intermittent one, which can make it more frustrating. On the one hand, it might take a long time to get your vehicle to start. On the other hand, your vehicle might simply refuse to start at all.

2. Engine Vibration Issues

Another sign that your crankshaft sensor might be faulty is an engine vibrating problem. Any such issue could signal a cylinder misfiring problem stemming from a failing crankshaft position sensor.

3. Fuel Economy Slippage

If your car crankshaft is not working optimally, one problem you'll face is reduced fuel economy. The reason for this is that your vehicle's fuel injectors won't direct gas to the motor efficiently.

This means your motor will make use of more gas than is required when you're out and about, which will result in lower fuel economy than normal. Of course, reduced fuel economy could be a function of other problems.

So it will be worth your while to go to an auto service center to have a professional assess the problem and to determine the right course of action.

4. Uneven Acceleration

Are you experiencing car issues such as uneven acceleration where it's hard to maintain a constant speed? This could be a sign of a failing crankshaft.

If your crankshaft sensor is not working properly, the motor control unit in your vehicle won't be able to execute the changes to the fuel injection or to the spark timing whenever the engine speed climbs.

5. Check Engine Light On

While a check engine light won't necessarily mean that your crankshaft sensor is failing, that doesn't mean that this can't be the case.

Because a check engine light could signal any of a number of problems, you'll want to use a code scanning tool to figure out what triggered the check engine light. You can also go to an automotive service center.

Don't Ignore Signs Signaling Possible Issues

If you've experienced any of the aforementioned signs of possible crank sensor problems, don't ignore them. You'll want to find a professional automotive facility that can assess the problem and find out what's wrong.

We're a dependable and reputable auto repair services provider. We can diagnose any problems, let you know if there's a problem, and then inform you of your options. For the help you need, don't hesitate to contact us.

In this article, we will go over one of the important sensors in the engine, commonly referred to as the “crankshaft position sensor”. Afterwards, you’ll understand its basic function, working principle, failure symptoms, and the replacement cost of this sensor.

Table of Contents

• How a Crankshaft Position Sensor Works
• Top 6 Bad Crankshaft Position Sensor Symptoms
  • #1 – Engine Vibrations
  • #2 – Check Engine Light
  • #3 – Weak Engine Performance
  • #4 – Trouble Starting Car
  • #5 – Engine Stalling
  • #6 – Cylinder Misfiring
• Crankshaft Position Sensor Replacement Cost

How a Crankshaft Position Sensor Works

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.

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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 Crankshaft Position Sensor 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 faulty 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. P0335 and P0336 are two common trouble codes that may be displayed.

Related: P0016, P0017, P1345 (Crankshaft/Camshaft Position Sensor Correlation)

#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.

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

Crankshaft Position Sensor Replacement Cost

Best places to order parts?  See: 19 Best Online Auto Parts Stores

If you experience at least two or more of the above 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.

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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