Boost Pressure Monitor
WARNING: This page is about a different car, the 2013 Ford F-550 Super Duty, 2013 Ford F-450 Super Duty, 2013 Ford F-350 Super Duty, and 2013 Ford F-250 Super Duty. 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.