MAP Sensor
Manifold Absolute Pressure sensor—an electronic sensor that measures air pressure in the intake manifold to help calculate engine load and fuel delivery.
The Manifold Absolute Pressure (MAP) sensor is a critical electronic component used by the engine control module (ECM) to monitor engine load. It measures the vacuum or pressure within the engine's intake manifold, which varies depending on throttle position and engine speed.
The ECM uses the MAP sensor's voltage signal along with engine RPM and air temperature to calculate the density of the air entering the cylinders. This method is known as the speed-density calculation, and it allows the ECM to inject the exact amount of fuel required to maintain an optimal air-fuel ratio. On turbocharged or supercharged engines, the MAP sensor also monitors boost pressure.
If a MAP sensor fails or becomes clogged with carbon deposits, the ECM will receive incorrect air pressure readings. This can cause the engine to run either too rich (wasting fuel and polluting) or too lean (causing engine knock and hesitation).
Common symptoms of a faulty MAP sensor include a rough idle, engine hesitation or stumbling under acceleration, poor fuel economy, failing emissions tests, and a check engine light with diagnostic trouble codes like P0105 through P0109.