Barometric Absolute Pressure Sensor
WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
The Barometric Absolute Pressure (BARO) sensor is part of MAP sensor mounted on left side of cowl, and monitors atmospheric pressure during ignition key-on, engine off. The signal is converted into an altitude value by the PCM. PCM uses this information to adjust fuel flow, injector timing and transmission shifting.