Boost Pressure Monitor
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 PCM determines if the correct amount of boost is being generated, in response to engine speed, load, manifold pressure and barometric pressure values. If the boost pressure is lower or higher than expected, a diagnostic trouble code (DTC) is stored and the malfunction indicator light (MIL) is illuminated.