Manifold Absolute Pressure (MAP) Sensor
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. 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.