What is a Camshaft Position Sensor and What Does It Do?

What is a Camshaft Position Sensor and What Does It Do

Several sensing devices are crucial to your car engine’s smooth operation. One of them, and one of the most important, is the camshaft position sensor. This sensor captures cam data, relaying it to the ECM for interpretation. The guide below is an overview of this sensor type. It will help you understand it better.

What is a Camshaft Position Sensor?

The camshaft sensor, or CMP sensor, is a monitoring component in an IC engine. It continually tracks the camshaft, sending data about its rotation and speed to the ECM or Engine Control Module.

The ECM needs this data to time engine operation, ensuring each cylinder is firing at the right time. Without the sensing device, the engine control system wouldn’t work as expected, leading to various issues.

In the auto parts world, this device is called the cylinder identification sensor. That’s because it detects when the first cylinder is at TDC.

Its use makes an engine more efficient. It also means a more powerful engine since the ECM can optimize fuel injection and sparking or ignition.

How Many Camshaft Position Sensors Are in a Car?

A vehicle may have one or more of these sensing devices. There’s usually one cam sensor in the engine. However, some have more than one and up to four.

In principle, vehicles without variable valve timing (VVT) have one, while those with VVT have two or four. Most have two, though. Four are rare to find.

Older engines that use a carburetor system have none. In these vehicles, there’s no need for TDC determination. They include those made in the 90’s or earlier.

Locating the cam sensor in a vehicle
Locating the cam sensor in a vehicle
Resource: https://www.youtube.com/watch?xI5NnK3uFds

Where is the Camshaft Sensor Located?

The exact location varies from one engine or vehicle to another. Most modern engines have it mounted at the top near the camshaft. In some, you can find it in the engine block or other components such as the flywheel or transmission bell.

That said, you can always use your car’s manual to find the exact location of this sensing device. Knowing its location can help you check it for damage, and if you’re a DIY enthusiast, replace it if it fails.

What Does a Camshaft Position Sensor Do?

The primary purpose of a camshaft sensor is to help the ECM compute ignition and fuel injection timing. It monitors the camshaft, sending data about its rotation.


That way, the ECM can use it to tell which engine cylinder is up for firing, which is in the exhaust stroke, and when it is appropriate to inject fuel or ignite fuel for optimal combustion.

Intake camshaft position sensor
Intake camshaft position sensor
Resource: https://www.hyundai-forums.com

Camshaft Position Sensor Function

The device performs several functions, all crucial to the engine’s proper functioning. These functions include sensing cam situation and spin, detecting engine misfires, and controlling the VVT operation.

Sense Camshaft Position

Position sensing is the most critical function of a cam sensor. It detects the cam as it spins alongside the crankshaft and helps the onboard computer to tell when the valves are opening or closing.

Determine Camshaft Speed

Another essential function is the determination of cam speed. The crankshaft rotates the camshaft, with the cam spinning at twice the crankshaft speed. The car computer uses the information to optimize engine operation.

Misfire Detection

In some vehicle types, the CMP sensor also helps the ECM detect when a cylinder misses a firing sequence. This information allows the computer to control the engine’s firing events.

VVT Control

VVT means variable valve timing. The CMP is responsible for its control. It does so by transmitting cam information to the computer, which, in turn, controls the valve opening and closing times while ensuring proper powertrain control.

The camshaft position sensor working principle illustrated
The camshaft position sensor working principle illustrated
Resource: https://www.youtube.com/watch?AAbSwQlczDU

How Does a Camshaft Position Work?

Its working principle involves interrupting a magnetic field or light beam with a trigger wheel. The wheel is usually located on the camshaft, rotating with it. The signal generated helps determine crucial cam parameters. In light of that, we have the following types of this device.

Magnetic Sensor

It utilizes magneto resistors to detect the cam position and direction of rotation. Magneto resistors change electrical resistance when a magnetic field perpendicular to the current direction is applied.

When the trigger wheel rotates, its effect causes resistance changes. An IC component and circuit pick and relay this signal to the ECM to help it calculate timing parameters.

Inductive Sensor

The inductive device is the most used type. It consists of a coil of wire wound around a permanent magnet. This construction creates a magnetic field around it. The rotating notched wheel disrupts this field, inducing a voltage in the coil.

The amount of voltage depends on whether the sensing element is presently aligned with a gap or tooth, while its frequency depends on how fast the can spins at that time. The ECM reads these pulses.

Hall Effect Sensor

This type relies on changes to the current of a semiconductor crystal by a magnetic field. It uses a permanent magnet and gallium arsenate crystal as the sensing elements. A voltage drop occurs when the magnetic field is disturbed.

“Hall effect” refers to this change caused by the movement of charges in the presence of a magnetic field. An electronic circuit uses the resulting pulses to generate an electric signal as a rectangular pulse of highs and lows.

The signal frequency varies based on the cam speed, and your car computer can use that to time fuel injection and ignition. These devices are compact, accurate, and reliable.

Optical Sensor

The optical type is a photoelectric device that uses a narrow beam of light to monitor the cam. The notches and teeth of the rotating wheel interrupt the beam as the cam rotates, and the resulting pulses determine various aspects of the camshaft.

Testing camshaft position sensor connector for failure
Testing camshaft position sensor connector for failure
Resource: https://www.youtube.com/watch?CfRKkHCYk6A

Can Camshaft Position Sensor Cause Misfire?

Yes, it can. The primary purpose of this sensing device is to monitor the cam. The engine control module uses this information to precisely regulate engine timing and ignition.

When this data is inaccurate or intermittent, issues start to appear. One is a misfiring engine or reduced fuel economy, among other problems. The check engine light may also come on, indicating a failing component.

A misfire happens when the fuel in a cylinder (or cylinders) fails to ignite or ignites weakly. In addition to reducing the power of your car’s engine, it can lead to increased emissions and other problems, such as poor acceleration.

That’s why you must change it as soon as you notice any signs of failure. It will go a long way in ensuring your engine performs optimally. Doing so also saves the engine from damage.

Conclusion

The camshaft sensor, CMP, helps the engine control systems ensure proper fuel injection and sparking or ignition timing. Without it, the engine performance and efficiency levels would drop, subjecting it to damage.

At WanTuo, we can supply you with the camshaft position sensor you need. We provide different types of these sensors. All our parts are designed to stand up to the harshest conditions and are 100% tested for quality and long service life. Talk to us now.

Louis
Louis

I'm Louis, a seasoned writer specializing in auto parts, particularly the science behind components like cylinder heads and pistons. With over a decade of experience and a background in mechanical engineering, my articles reflect a commitment to professionalism, blending technical insight with engaging content.

Leave a Comment

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

Table of Contents
Contact us
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Related Posts
What is a Hydraulic Roller Camshaft
Hydraulic Roller Camshaft Guide: What is it & Advantage

The hydraulic roller camshaft combines a rolling lifter and hydraulic mechanism into one unit, providing benefits that range from quiet operation to automatic lash adjustments. This guide will help you understand what these cams are, what they look like, and their advantages over solid types. So, let’s dive right in. What is a Hydraulic Roller

Camshaft Sensor vs. Crankshaft Sensor: What is Different?

The modern engine runs far more efficiently, thanks to various sensing devices. This article covers two of the most critical sensors in your car engine: camshaft sensor vs. crankshaft sensor. We will see where to find each, their different functions, and other essential information about them. Are the Camshaft Sensor and Crankshaft Sensor the Same?

What is a Camshaft Position Sensor and What Does It Do
What is a Camshaft Position Sensor and What Does It Do?

Several sensing devices are crucial to your car engine’s smooth operation. One of them, and one of the most important, is the camshaft position sensor. This sensor captures cam data, relaying it to the ECM for interpretation. The guide below is an overview of this sensor type. It will help you understand it better. What

What is a Billet Camshaft
Billet Camshaft Guide: What is it, How it Made & Advantages

If you’re buying camshafts, you’ll come across these two different types: the cast and billet camshaft. Billet cams are tougher. However, you’ll find that they cost more. Cast types are cheaper but less reliable in extreme lift and spring pressures, especially at higher RPM. Here, we’ll help you understand what billet cams are, their manufacturing

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Contact Info