In modern automobiles, the ignition system is a very complicated component of the car, and uses some of the most advanced computers in order to track the movements of the engine. In order to correctly run the engine, this computer needs detailed data on how the pistons are firing and how the cylinders are moving. The cam (or to give it is full name, camshaft) sensor helps give the computer necessary data.
The camshaft is a metal bar that uses a series of protrusions known as cams to open and close the valves used to bring in the air/fuel mixture to the piston. The valves discharge the exhaust as the piston pumps. The camshaft spins around, opening and closing valves for each piston as necessary. This happens extremely fast, and the cam sensor is a small device located on the camshaft that senses which cylinder is currently being used.
While the camshaft sensor cannot control the speed of the engine, it can give the car's computer valuable information about which cylinder is currently being used. As the camshaft moves from cylinder to cylinder, the sensor can tell the ignition system which piston is currently being fired. The computer uses this information to either speed up or slow down the fuel injection and operation of the engine as needed.
Cam sensors also give the computer information about how the fuel injection system is firing into each cylinder. This allows the computer to plot the order of fuel injection correctly.
The data from the cam sensor is usually calculated together with the data from the crankshaft sensor. Since the crankshaft is directly affected by the movement of the pistons, it provides a very clear picture of how fast the engine is running. The computer can use both sets of data to create clearer results of the state of the engine and if any process needs adjustment.
Because the crankshaft and camshaft sensors are similar, troubleshooting one or the other can be difficult. Usually if the cam sensor is not working the engine will refuse to turn. A mechanic will usually need to test each sensor individually if it looks like something may be wrong with them.
