Boost Pressure Monitor
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2016 Ford Transit-350 HD, 2016 Ford Transit-350, 2016 Ford Transit-250, 2016 Ford Transit-150, and 2016 Ford F-550 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.