The intake manifold of an engine may be equipped with a “Manifold Air Pressure sensor”, abbreviated as MAP sensor. This pressure sensor measures the absolute pressure in the intake manifold. The sensor can be mounted on the intake manifold, or connected externally by means of a snake. The under or overpressure is converted by the sensor into a signal voltage that is created from the supply voltage. This makes the MAP sensor an active sensor.
The measuring range is often from 20 – 300 kPa (0.5 to 3 bar). We distinguish between the MAP sensor for a naturally aspirated engine and a boost pressure sensor for an engine with boost pressure control. MAP sensors are used to measure engine load. The manifold (under) pressure is a measure of the degree of filling. The fuel injection is determined, among other things, from the value that the MAP sensor registers.