Car System

6 Common Signs Of Bad Crankshaft Position Sensor

Mike Cross
Updated Oct 18, 2020
Signs of Bad Crankshaft Position Sensor

Your vehicle has a lot of different sensors, and one of those sensors is the crankshaft position sensor. Another name for that sensor is the ESS or engine speed sensor. This sensor plays a vital role in how well your car runs. Most people though aren’t even aware of this sensor, and most don’t know what it does. Well, in this article we will explain what the crankshaft position sensor does and why it is important. We will also look at symptoms of a failing crankshaft position sensor so that you can diagnose a failing one on your own.

Signs of Bad Crankshaft Position Sensor
Signs of Bad Crankshaft Position Sensor

What does it do?

First, before going into details of what to look for with a crankshaft position sensor that is going bad, we will first explain what it does and the purpose behind it. The crankshaft position sensor is responsible for monitoring the crankshaft and make sure it stays aligned or in the proper timing with the rest of the engine. The ESS looks at the crankshaft and sees what position it is in. It then sends this information to the engine control unit, and that is how it knows which cylinder to fire. The engine speed sensor also keeps an eye on how fast the crankshaft is rotating. This is the RPM or rotation per minute dial you see on the dash. The reason the RPM is important is what is how the car chooses what gear to have the transmission in. If the crankshaft position sensor goes bad or starts to go bad, then the car will start running poorly.

Signs of Bad Crankshaft Position Sensor

A lot of the signs that come with a failing crankshaft position sensor have to do with the engine and how well the car runs. This should make sense because like has been mentioned the sensor controls what gear the car is in and also what cylinders are firing. If it is sending the wrong signal, then the wrong sensors could fire, or the car could be in the wrong gear. This can cause a lot of damage to the engine and the transmission. That is why if you notice the symptoms below, you should have your car checked out as soon as possible.

1. Engine Code

The first sign of a bad crankshaft position sensor is a check engine light.

When you have a check engine light, you should always have your car's computer scanned with the best OBD2 scanner as soon as possible.

The car telling you something is wrong is a good way to catch a problem early before it becomes bigger. If you have a check engine light, have the cars computer scanned and if the code is for the crankshaft position sensor, then have it replaced.

2. Trouble Starting

Sometimes though the computer won’t notice a problem with a sensor. This is especially true if it is just in the process of starting to fail, but hasn’t all the way. The next thing to pay attention to when it comes to the ESS is when you start the car. If the car struggles to turn over, then that is a good sign that the crankshaft position sensor might be faulty. That is because it starts monitoring the crankshaft right away and this helps the car to start to know which cylinders to fire. When starting the car, there are only a few things that could keep it from starting, so the problem is easier to find during this step.

3. Engine Misfires

Sometimes though the car will start fine and then the sensor will start to cut out while driving. If this happens, then you might start having engine misfires. The problem with just going by misfires though is that it could be a lot of different sensors that could be going bad.

If you start to have misfires and don’t have an engine code, then you will start having to check the different sensors that help the vehicle run. The crankshaft position sensor is one of them, and if the others check out fine, then you should check it because it might be the sensor that is failing.

4. Engine Stall

Again if your engine stalls while driving, then it could be a variety of sensors causing this problem, but it means you have an issue and need to investigate. For the crankshaft position sensor, a lot of times the engine will stall at slower speeds. If you have an engine that is stalling which means shutting off randomly, then you should have all your sensors checked out till you find the bad one that is causing your car not to run properly.

5. Loss of Fuel Efficiency

The next symptom of a bad or failing crankshaft position sensor is a loss of fuel efficiency. Not everyone keeps track of their mileage, but you should because a change in fuel efficiency can be an early sign of a lot of potential problems. The reason that your fuel efficiency will start to suffer from a bad crankshaft position sensor is that since the timing of the car is off too much fuel might be going into the cylinders because it might be having the engine fire the wrong cylinders. This will cause damage to the engine as well as loss of mileage.

6. Acceleration Problems

Outside of engine problems you might also start to experience acceleration problems. That is because the ESS is responsible for monitoring how fast the crankshaft is rotating and establishing the RPMs of the engine. It then uses this information to pick the gear the car is in. If the sensor is not reading your speed right, then it won’t change gear correctly, and this will make it harder to accelerate. On top of this, you might also experience a loss of power with your vehicle. This is again because the car might be operating at a gear less than what it should be.


So, now you know all the signs of a failing crankshaft position sensor. You know that most symptoms have to deal with the engine and the car not firing correctly, but some have to do with how the car accelerates. You know the big one to pay attention for is a check engine light and that the car should be scanned whenever it comes on so you can have the problem fixed right away. Making sure all your sensors are working right is important to keep your run working properly longer. This is especially true with your crankshaft position sensor because if it is bad, then your engine can suffer a lot of damage. That is why it is key to be aware of the symptoms of a bad crankshaft position sensor, so your car will stay running properly at all times.

Mike Cross
Life is too short to drive with stock audio

Leave a Reply

Your email address will not be published. Required fields are marked *

3 comments on “6 Common Signs Of Bad Crankshaft Position Sensor”

  1. 2001 Chevy Silverado backfiring when you drive it I did unplug the mass airflow sensor but I drove like that for a week or so could that still be the cause of the backfiring and loss of power when I drive it and put a load on it

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram