Manifold Absolute Pressure (MAP) Sensor
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, 2011 Ford Fusion, 2010 Mercury Milan, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The MAP sensor uses a piezo-resistive silicon sensing element to provide a voltage proportional to the absolute pressure in the intake manifold.
The MAP sensor is part of the EGR system. The PCM uses information from the MAP, TP, MAF, CHT and CKP sensors to determine how much exhaust gas is introduced into the intake manifold.