Barometric Pressure (BARO) Sensor
WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The BARO sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the powertrain control module (PCM) and returns a voltage signal to the PCM relative to the intake manifold pressure. The sensor voltage increases as the pressure increases. The BARO sensor is integral to the PCM.