Theory Of Operation
WARNING: This page is about a different car, the 2012 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Diesel Exhaust Fluid (DEF) Supply Pump Assembly has an internal temperature sensor which reports the internal temperature of the DEF Supply Pump Assembly to the DEF Dosing Control Unit. This fault is triggered if the DEF Supply Pump Assembly Temperature Sensor is different than the other temperature sensors on the engine. This indicates an internal problem in the DEF Supply Pump Assembly.