Theory Of Operation
WARNING: This page is about a different car, the 2019 RAM 3500 HD and 2019 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the intake air flow, and controls the variable geometry turbocharger (VGT) position to obtain the correct amount of fresh air and exhaust gas recirculation (EGR) for the injected amount of fuel. The PCM compares the actual air flow (calculated using multiple sensors in the intake air system - Mass Air Flow, Boost Pressure, and Temperature sensors) versus a commanded air flow. If the actual charged air flow is greater than the commanded flow by more than calibrated amount for a calibrated period of time, this diagnostic will fail.