The manifold absolute pressure sensor or MAP sensor is a sensor that is attached to the intake manifold on a car’s engine. The MAP sensor responds to changes in the intake manifold pressure (vacuum) and provides a reading of the “engine load”.
Its operation is based on 5 volts DC supplied to the sensor by the PCM (powertrain control module). Inside the MAP sensor, there is a resistor that moves according to the intake manifold pressure. The resistor varies the voltage between about 1 V and 4.5 V (depending on the engine load) and this voltage signal is sent back to the PCM to indicate the intake pressure (vacuum). This signal is essential for the PCM to determine the fuel flow rate and is also used repeatedly to determine if the EGR valve is functioning properly.
