Barometric Pressure (BARO) Sensor
WARNING: This page is about a different car, the 1995 Ford Bronco. However, it is still accessible from the selected car via links, so may be relevant.
BARO sensor measures barometric pressure of atmosphere. Variations in atmospheric pressure (changes in altitude) modify an electrical signal monitored by PCM. The BARO sensor input affects spark advance, EGR flow and air/fuel mixture adjustments by PCM. Sensor input is updated during key-on and wide open throttle applications.
The BARO sensor looks the same as Manifold Absolute Pressure (MAP) sensor, except the tubing nipple on BARO sensor is vented to the atmosphere and MAP sensor is connected to the intake manifold.