When Monitored
WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Engine Running. When the Exhaust Gas Temperature (EGT) 3 Sensor, Diesel Exhaust Fluid (DEF) Tank Temperature, and the Ambient Temperature Sensor all reach a calibrated threshold in a pre-determined amount of time. The Powertrain Control Module (PCM) then begins to monitor the DEF system as it attempts to prime the DEF Pump.