How to Replace a Camshaft Sensor

If the engine on your vehicle suddenly isn’t running well, there’s a good chance it’s an issue with something electrical, not mechanical. With the plethora of sensors and wiring under the hood, one small problem can cause a range of symptoms. That’s true for the camshaft sensor, or camshaft position sensor.

The small but extremely important cam sensor can range from about $15 on some vehicles to several hundred dollars on others. Fortunately, it’s often an easy part to change, and it will have your engine running well immediately after the repair. Here’s what you need to know about changing a camshaft position sensor.

What does the camshaft sensor do? 

A camshaft sensor is a device that monitors the position of the camshaft in an engine. It sends this information to the engine control unit, which uses it to regulate the engine’s operation. The camshaft sensor consists of a cylindrical body with a protrusion on one end. The protrusion often uses the Hall principle, meaning that the sensor voltage changes based on its proximity to the camshaft’s ring gear. Of course, this means that the cam sensor is positioned near the top of the engine, typically mounted in the cylinder head, the cylinder block, or in the timing cover. 

When an engine is running, the camshaft sensor’s position is constantly changing as the camshaft turns. The sensor produces an electrical signal that is proportional to the camshaft’s position. This signal is sent to the engine control unit, which uses it to determine the correct timing for fuel injectors and ignition coils. 

Symptoms of a bad camshaft sensor 

If the camshaft sensor is not working properly, the engine will not run correctly. It’s because the engine control unit doesn’t know what position the camshaft is in, so it’s unable to adjust the timing and other key operations for the engine to run smoothly and efficiently.  

Symptoms of a faulty camshaft sensor include: 

  • Engine misfires 
  • Rough idling 
  • Poor fuel economy 
  • Check Engine light is illuminated, typically with code P0340 

If it’s reading incorrectly at times and functions properly at other times, your symptoms might be intermittent. In other cases, the symptoms are constant until the sensor has been replaced. 

What causes a camshaft sensor to fail? 

The cam sensor is designed to last a very long time. For a lot of vehicles, it will last its entire lifespan without needing to be replaced. On others, it’s a common point of failure.  

There are several things that can cause a camshaft position sensor to fail, including: 

  • Moisture or dirt getting into the sensor. If the resistance changes in the sensor due to moisture or dirt, it will affect the reading that’s sent to the engine control module. The false or disrupted reading will cause incorrect adjustments for timing and fuel. 
  • The sensor getting hot enough to melt. If the sensor body is exposed to extreme temperatures like from the engine overheating, it could melt. 
  • The connector coming loose or breaking. The retaining clip on the electrical connector could become brittle and break, or it could wiggle loose. Whether moisture penetrates the connector or the terminals corrode, the sensor won’t operate properly. 
  • The wire harness being damaged.  

Steps to change a camshaft position sensor 

Changing a cam sensor isn’t an overly complicated job, but it requires some basic tools and a code reader to get the job done right. 

1. Disconnect the negative battery cable

For any work on the electrical system or engine, disconnect the battery first to prevent accidental short circuits.

2. Locate the camshaft sensor

You may need to take off the engine cover if it has one. Then, find the camshaft sensor either at the timing cover, on the cylinder head, or on the side of the engine block. It will be mounted near the top, and will have a wiring connector attached to it. There could be two, three, or four wires in the connector.

3. Remove the connector

To prevent unnecessary movement, the connector is usually fastened in place. Remove the bolt or screw holding it, then disconnect the connector, being careful not to break the plastic.

4. Remove the sensor

Next, remove the fasteners holding the sensor into the engine. Often, it’s two bolts you’ll need to remove. Keep them safe since the hardware isn’t included with the new sensor.

5. Take the cam sensor out

Lift the sensor out of the engine and remove the O-ring seal from the hole in the engine block. It might take a firm wiggle and twisting motion to unseat it. Take extreme care not to pry on it as the sensor could break, requiring significantly more work to extract it.

6. Install a new O-ring seal

The O-ring prevents oil from exiting the sensor’s hole and keeps dirt on the outside. You should install a new O-ring in the hole in the engine block.

7. Install the sensor

Position the new sensor in the same orientation in the engine and secure it with the two bolts. Use the correct torque spec to prevent cracking the new part. Reconnect the sensor’s wiring connector and connect the negative battery cable.

8. Clear the existing codes

Using a code reader, clear the Check Engine light to prevent the old codes from creating ongoing issues. Fire up the engine and, if your code reader is equipped with a monitoring feature, check that there aren’t any new or pending codes and that the cam sensor is reading correctly.

How much does a camshaft sensor replacement cost? 

The new cam sensor is relatively inexpensive for most vehicles with prices commonly between $20 and $150. It’s a quick job that makes a big difference in how your vehicle runs, and you can often get it done within an hour or so. Change it yourself to save the price of labor, or if you decide that it’s too big a job to tackle on your own, let AutoZone help you find qualified professional mechanics through our Shop Referral Program

Get your new camshaft position sensor at AutoZone. Ask our associates for Trustworthy Advice, borrow a code reader through our Loan-A-Tool program, or explore any other parts and accessories you might n need to get the job done right.

Do you need a more in-depth look into your vehicle to help you with your project? ALLDATA, the leading provider of automotive repair information, is now providing DIYers with the same information that the pros use with ALLDATAdiy’s single-vehicle subscriptions.

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Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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