An engine speed sensor, not to be confused with the vehicle speed sensor, is a sensor that is attached to the crankshaft of your car's engine.
How the Engine Speed Sensor Works
Being attached to the crankshaft of the vehicle's engine, the engine speed sensor is meant to assess the speed at which the crankshaft spins. The device is basically a metal disk that has a serrated (toothed) circumference. In addition, there's a stationary device containing a magnetic coil, which acts as a standard for the measurement. When the crankshaft spins, induction current is set up around the magnetic coil. The serrated edge of the crankshaft obstructs the produced magnetic field and this is recorded. This is what gives a measurement of the amount of current produced, which is outputted as the speed of the vehicle's engine.
The engine speed sensor becomes an important device because it provides a real value for the engine's speed. Since every car has its own specific speed limit, this device is put into use when checking the overall performance of the car.
Problems with an Engine Speed Sensor
If your vehicle has a faulty engine speed sensor, you will generally experience a problem with the air to fuel ratio and close associations with the coolant sensor. If you are having trouble with cruise control and speedometer issues, this will be attributed to the vehicle speed sensor.