Camshaft Position Sensor

Electronic fuel injection systems rely on a number of sensors to control the delivery of the fuel and air mixture to the engine. One of these is the camshaft position sensor which uses the hall effect principle to detect when a magnet on the camshaft passes in front of it. Although it has no moving parts, the sensor is still subjected to the extreme heat and vibration of the engine and will eventually fail over time. Replacing a camshaft position sensor is an inexpensive and simple task which can be done by most people with a few basic tools.

Electrical sensors that use the hall effect principle act as a switch when they are subjected to a magnetic field. As the strength of the magnetic field changes, the sensor changes the flow of current through it. The field does not have to be very strong to influence these sensors so only a small magnet needs to be used. This is especially important for reducing vibration in components that rotate at high speed, such as a camshaft. The camshaft position sensor allows the fuel injection system to know when the engine values are open or closed by detecting when current is flowing through the sensor.

Some fuel injection systems are intelligent enough to know when the camshaft position sensor has failed, while other systems only signal a general fault that could be caused by any of the sensors used. Before replacing the sensor, first check the plugs and wiring for signs of breakage or corrosion. The sensor is a solid component with no moving parts so it is unlikely to be the cause of the failure. If the sensor is suspected of being the problem, a basic test can be performed with a multimeter.

The camshaft position sensor is a small component that is located near the top of the engine casing. It can usually be accessed without having to remove other engine components, which saves a lot of time and allows the sensor to be changed fairly quickly. The sensor is held in place by a couple of small bolts which can be easily removed with an adjustable wrench or socket set. It is connected to the fuel injection system by a plug with two wires, which also need to be removed and reconnected to the new sensor.

Remove the bolts holding the camshaft position sensor and pull it out of the engine casing. Connect the terminals to the multimeter and set it to either a low resistance setting or the diode test function. Pass a magnet in front of the sensor several times and look for a change in the reading. A working sensor should create a significant change in the reading as the magnet passes in front of it, while a broken sensor would should no change.

There are many different sizes and housing used for the camshaft position sensor. Before purchasing a new sensor, check if it is suitable for the make and model of the vehicle. A badly fitted sensor will allow hot gases and oil to escape and possibly damage the sensor and other engine components. Always use a new seal when installing a new sensor, and coat it lightly with oil to reduce wear as the sensor is bolted down. The polarity of the wires is not usually a problem with these sensors but it should be checked anyway before fitting the plug.

After installing a new camshaft position sensor, start the engine and check if there are any leaks coming from the sensor port. If the fuel injection system is still signaling a fault after a new sensor has been installed, there is possibly a more serious problem that requires servicing by a mechanic. They will have more sophisticated equipment that is capable of finding the true cause of the problem.

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