Symptoms Of A Bad Camshaft Position Sensor And Replacement Cost

How can you tell if your car has a bad camshaft position sensor? This guide shows you all the symptoms and what the expected replacement cost is.

The camshaft is a very important component of the car engine. Its biggest task is to operate the intake and exhaust valves, it may also drive other components such as the fuel pump, oil pump, and power steering pump.

Considering that the camshaft is in charge of maybe the most important thing in the car, which is determining the intake and exhaust rate, many symptoms may occur if something is defective.

It may be a bit tricky to distinguish the camshaft from the crankshaft, not only because of the similar name but also because they work together.

The camshaft is connected to the crankshaft by a timing belt or timing chain. This is important as the crankshaft also determines the positioning of the pistons, making the whole process synchronous.

If the camshaft position sensor is faulty, the synchronous process may be disturbed leading to multiple symptoms.

In this article, we will cover everything about a bad camshaft position sensor, including the replacement cost and diagnosis.

To learn more about how everything works to make your car move, make sure to check out our article on how a car engine works.

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What Is A Camshaft Position Sensor?

car camshaft position sensor

Just like crankshaft works together with the camshaft, so do their respective sensors. The camshaft position sensor sends information to the engine control unit which in turn uses that information to power the engine.

The engine control unit and camshaft, together with its sensor make sure that the appropriate amount of fuel and air gets added to the combustion chamber and that it ignites exactly at the right moment.

If it turns out that the camshaft is not functioning properly, your car could have problems starting, accelerating, or stalling.

Symptoms Of A Bad Camshaft Position Sensor

faulty camshaft position sensor

As a camshaft position sensor plays an important role, many things can arise if it is bad.

The most common symptom that occurs are the following:

  • Check engine light
  • Stalled engine
  • Unable to start the car
  • Rough idle
  • Reduced engine power
  • Bad gas mileage

All these symptoms may show up individually or together. In most cases, the check engine light will illuminate together with one or more of the symptoms.

In the text below, each of the symptoms listed will be explained so you can get a better picture of the problem that lies with the camshaft position sensor.

Check Engine Light

car check engine light on

The most common symptom of a bad camshaft position sensor is a check engine light that illuminates.

As always, when the light comes on, it is very hard to differentiate what the problem is. In order to get a clearer picture, you should scan your car for any error codes with an OBD2 scanner.

If you do not have an OBD2 scanner, you could always take your car to the mechanic. Generally, you should not drive your car if the light illuminates, as more damage may be done.

If you do know the cause of the check engine light, you may drive the car to the shop, provided that a professional mechanic or alike has given the green light.

In many cases, the so-called “limp mode” might engage. This is a safety feature that restricts the power and speed of your car in order to protect all the components.

Generally, you can drive your car to the nearest shop if limp mode is engaged. Just like the check engine light, the limp mode might disappear when you turn your engine off and on again.

Stalled Engine

woman on phone opens car hood to look at engine

A more serious, and luckily, a rare symptom is that the engine stalls. This might happen when you are at your parking space or when you are driving on the road.

The latter scenario is extremely serious. Therefore, if you notice that your engine stalls unexpectedly, do not drive the car at all.

This problem is caused as no combustion takes place as no fuel or air goes into the combustion chamber at the right moment.

Unable To Start The Car

man inserting key in car ignition lock

This symptom is related to the one above. As the sensor does not work optimally, the engine will have a hard time turning on.

As with almost any other symptom, this might be due to a lot of reasons. Other reasons why a car won’t start might be due to a faulty starter, clogged fuel filter, dead battery, or due to other reasons.

Rough Idle

opening the hood of a broken car

When everything is as it should, very few appreciate a nice and steady idle. However, when the idle is rough it is very noticeable for the typical car guy or girl.

If the camshaft position sensor is faulty, the rough idle is due to the unsynchronous combustion taking place in the cylinders.  

A rough idle might also be a consequence of a faulty fuel pump or EGR valve. Whatever the cause, it is important to know what causes the rough idle. It may take some further tools and testing to do so.

Reduced Engine Power

car engine

Reduced engine power comes in two ways. Either the reduced power is due to the limp mode, as a precaution, or no message is or light in the dashboard is seen, and the car drives roughly.

You may notice the reduced engine power when accelerating or simply a drop in engine speed when coasting or idling.

It may also present as vibrations when accelerating. All of this is due to ineffective combustion and misfires happening in the cylinders of the engine.

Bad Gas Mileage

how to improve gas mileage

As the camshaft sensor gives wrong information to the engine control unit, an abnormal amount of fuel may be injected into the combustion chamber.

Not only will more fuel be injected, but the combustion will also occur at a sub-optimal time, leading to more unburnt fuel, and in turn a bad gas mileage.

This symptom may be harder to notice as it happens during a prolonged time and you as a driver have to be aware of the usual fuel mileage your car gets.

Replacement Cost For A Camshaft Position Sensor

camshaft position sensor replacement

If it turns out that your camshaft position sensor is bad, you will need to replace it with a new one. If you are familiar with working on your car, you could even do it yourself!

Changing the sensor is not very hard, but it might lie in a location that is difficult to reach. Therefore, it may take some patience to replace it.

In terms of buying a new sensor, it will cost, on average, $90 to $140. The labor cost will set you back $70 to $100.

As with every other replacement, the cost is affected by the type of car as well as the repair shop. Premium brands and dealerships are almost always more expensive.

Either way, expect to pay a total of $160 to $240 for a camshaft position sensor replacement.


auto camshaft position sensor

The camshaft position sensor is a small, but very important for your car’s engine. It makes sure that fuel and air combust at the right time in the combustion chamber of the engine.

It works closely with the crankshaft as well as the engine control unit. If the sensor does not work properly, many symptoms may occur.

Usually, a check engine light will turn on. Other symptoms include bad gas mileage, rough idle, engine stalling, and engine power loss.

All of the symptoms might be hard to differentiate. In most cases, it is best to leave your car to a professional mechanic and fix the problem.

A broken camshaft position sensor has to be replaced and will set you back a total of $160 to $240. The price depends on what car you drive as well as the repair shop that does the work.

If you have the right tools and patience, you could also change the sensor yourself. In that case, the only thing you would have to do is buy a new sensor which costs between $90 to $140.

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Bajro Muric
Bajro Muric

Bajro is a big car enthusiast with a love for writing and teaching. He writes about anything regarding cars - from common problems and fixes to racing.