Symptoms of a Bad Crankshaft Position Sensor & How Much It Costs to Replace

This is all great and when things are working as they should it makes our lives easier. The trouble is though the more technology we have the more things there are that can potentially go wrong. Some sensors are more important than others.

In this article we will be looking at one of the important sensors, the crankshaft position sensor. We will explain the signs that this sensor may have failed and also discuss the potential cost of having it replaced. So if you feel this sensor may be at fault in your vehicle read on.

What Does the Crankshaft Position Sensor Do?

As the name of this sensor suggests the crankshaft position sensor literally does just that, it monitors the position of the crankshaft. You may not think this is a necessary sensor but in fact this can be vital information.

This sensor sends measurements to the car's electronic control module (ECM) which in turn uses this data to optimize the rest of the engine's timing. If the sensor fails then the ECM has no option but to assume default values and if these are not correct then you may suffer performance issues.

Sometimes however the sensor will just be sending incorrect measurements and the ECM does not realize this. In many ways this is worse as the likelihood is that the measurements will be vastly incorrect and can potentially lead to damage in the engine.

Where Is the Crankshaft Position Sensor?

As you might imagine the crankshaft position sensor will be located close to the crankshaft itself. This usually means that it is located near the bottom of the engine. As a result they can be hard to locate without being under the vehicle.

Unlike some sensors replacing this part is trickier due to its location. This can mean higher costs in terms of labor as it will take more physical work to perform the replacement.

Indications of a Bad Crankshaft Position Sensor

The symptoms of a bad crankshaft position sensor are also indicative of a number of other issues so it is hard to easily diagnose this issue with symptoms alone. As a result you will likely need to get a mechanic to check out the situation or purchase an OBD2 scanner tool to fully confirm this sensor as the issue.

There are however some very clear symptoms that may indicate the crankshaft position sensor may be at fault. So read on to find out what you should be looking out for.

Check Engine Light

The dreaded check engine light is the warning for a whole host of engine issues and the crankshaft position sensor is just one of them. When this light illuminates on your dashboard you are going to want to do just what it says and check your engine.

Assuming the check engine light has come on because of the crankshaft position sensor there is a little good news. The ECM has realized that the sensor is not working and it will now be working off those default settings.

As mentioned when default settings are being used you may lose performance but the operation should at least not cause any further damage. If the ECM does not know the sensor readings are faulty however you won't get the warning light and your engine is at risk from damage.

Engine Misfires

If you have ever heard the term engine misfires you may be aware how damaging they can be to your vehicle. Assuming you have the check engine light displaying you likely will not have misfires with a crankshaft position sensor failure.

If the issue is bad readings from the sensor however you can get misfires. This is because the ECM will react to bad information which can lead to poor air/fuel mixtures in the cylinder. As a result the normally optimal combustions in the cylinders may be too lean or too rich. This over time can cause misfires and costly engine damage.

Engine Stalling

Wildly inaccurate position data from the crankshaft position sensor can lead to the ECM not only messing up the air/fuel mixture but also the ignition timing. As a result you may find the vehicle stalling frequently.

This doesn’t usually happen immediately after an issue starts with the sensor so it is generally a sign that the part has been working poorly for some time. As a result you will likely be looking at additional repairs should you allow it to get to this point.

Engine Vibrations

Controlled small explosions in your engine are required to make it work so you must expect a certain amount of vibration, this is normal. However if the ECM is receiving inaccurate data from the crankshaft position sensor then it will cause the engine to run roughly.

The result of a poorly performing engine can be excess vibrations as timing may be off creating misfires. You may hear bumps while idling and more noticeable vibrations if this is the case.

Engine Performance Drops

Whether the crankshaft position sensor fails completely or is just sending incorrect readings you will see a change in engine performance. This is because the exact position of the crankshaft will never be fully known if the sensor is not working so the optimal conditions can not be created by the ECM.

Without the right conditions your engine will not run as well meaning you will notice less power, a dip in acceleration and overall rough operation. This will also have a knock on effect on your fuel economy. Your engine will use more fuel to produce this weakened performance.

Issues Starting the Engine

If the crankshaft is vastly out of position compared to what the ECM is being told by the sensor you might find that even starting your engine is problematic. This usually only develops after the sensor has been at fault for a while so essentially if you ignore the issue.

Again this is an issue when the sensor is sending incorrect readings rather than a completely failed sensor that has caused the ECM to use default settings.

How Much Does It Cost to Replace the Crankshaft Position Sensor?

Prices for a new crankshaft position sensor can vary on your type of vehicle but on average the part alone can cost between $150 - $250. A more high end vehicle may require a part that costs a lot more so be aware of this.

In terms of labor costs you may be looking at between $90 - $110 for a mechanic to complete the work. Of course if you have the right equipment you may be able to do the job yourself for the price of the parts.

Remember this is not a repair you will want to put off until later. If your engine is running incorrectly because of this sensor it can develop damage. Spending a few hundred dollars to fix this issue can save you potentially thousands should the fault further damage the engine itself.

Conclusion

The crankshaft position sensor is key to a smooth running engine that will give you optimum performance. If it fails completely your ECM will revert to default readings and may decrease your performance.

Things can get serious however if the sensor is simply damaged but just sending incorrect readings. The ECM will believe these readings and this can cause very bad performance and overtime serious damage to your car's engine.

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