The camshaft position sensor: what is it and what does it do?

The camshaft position sensor is a small but vital part of keeping your engine healthy. While it flies under the radar when all is well, if your camshaft position sensor starts to fail it can cause chaos in your engine. Stalling, engine misfiring, and rough idling are just a few of the issues that may crop up.

But what does it do, and how do you know when it fails? Let’s take a look at everything you need to know about the camshaft sensor.

What is the camshaft sensor?

This little chunk of plastic and metal keeps tabs on what your camshaft is doing, playing a vital part in keeping your engine performing at its best. Without it your engine's computer doesn’t know what’s going on or what it needs to do. Essentially the camshaft position sensor is a messenger between your camshaft and your car’s ECU, which is an essential element of the engine management system.

What does the camshaft positioning sensor do?

The function of the camshaft position sensor is to monitor the speed that the camshaft is rotating at, while also keeping tabs on its position. It then relays this information to the ECU (Engine Control Unit). The ECU uses this data to adjust the timing of the spark plugs, and how much fuel is injected into the cylinder so that your engine runs smoothly.

Where is the camshaft position sensor?

Pop the bonnet and take a look underneath the engine cover. The camshaft position sensor location varies based on your car make and model, but it will be either on the cylinder head, tucked behind the spark plugs, or on the side of the engine. Depending on the age of your car there may be more than one sensor, with newer cars typically having one for each camshaft.

What are faulty camshaft sensor symptoms?

Here are a few camshaft position sensor symptoms that could mean your sensor is on the way out:

What happens when a camshaft sensor goes bad?

If your camshaft sensor has failed completely, your engine could be in strife. While you might just experience symptoms such as rough idling, a misfiring engine, and trouble getting the car started, you could end up with complete engine failure. That’s why getting your car looked at when issues first arise is so important.

How to check if camshaft position sensor is bad

If you see your check engine light coming on and it’s your camshaft position sensor, your ECU will show a camshaft position sensor fault code. These codes include P0340-P0344 and can be caused by a faulty camshaft position sensor, but can also be caused by a faulty camshaft, damaged wiring, or a faulty ECU. So the next step is to check the sensor is receiving the right voltage from the ECU and that it has a good ground connection.

You can do the following a camshaft position sensor test to see if the fault is with the sensor itself:

1. Turn the ignition off and disconnect the sensor

2. Refer to your vehicle's wiring diagram to identify the connection terminal for the camshaft sensor

3. Turn the ignition back on

4. Set your multimeter to Volts DC

5. Place the red probe on the 5V terminal on the sensor, and your black probe on the negative terminal of the car battery

6. Check the reading on the Multimeter—it should show 5 volts

7. Keeping the black probe on the negative terminal of the car battery, move the red probe on to the sensor signal terminal—this should also read 5 volts

8. Then check the ground connection by moving the red probe to the positive side of the battery, and move the black probe onto the ground terminal of the sensor—it should read around 12.6 volts

If all three readings are as they’re meant to be, then your sensor is functioning as it should be and the problem is with one of the other components. If you’re unsure and need advice, it’s a good idea to take your car into a nearby mycar for an inspection.

How much does it cost to replace a camshaft sensor?

On average the camshaft sensor replacement cost will be around $220-$450. The costs will vary depending on the camshaft sensor price for your car make and model, and labour time needed to do the replacement.

What to do after replacing camshaft sensor

Once your camshaft sensor has been replaced you should evaluate how your engine is running. Check that your engine idles and runs smoothly, that no unusual noises can be heard and that no warning lights are illuminated.

Can I drive with a bad camshaft position sensor?

While you can drive with a bad camshaft position sensor, it’s not recommended. Continuing to drive with a faulty sensor can lead to other more costly problems, and it could potentially cause your engine to stall while you’re on the road, causing danger to yourself and others.

Still not sure? Drop into mycar for help

If you’ve been experiencing any of the symptoms of a faulty camshaft sensor, or just need a check-up to ensure your vehicle is in tip top shape, drop in your local mycar. With more than 275 stores across the country, our friendly team of experts are just down the road and ready to help you out. And with our workmanship guarantee you can rest assured your car is in the best hands.