Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Selective Catalytic Reduction (SCR) Catalyst is used in combination with the Diesel Exhaust Fluid system to reduce the amount of NOx gases produced during engine combustion. Excessive fuel or oil entering the exhaust system due to a failed engine component or Fuel Injector can cause the temperature to rise and will result in damage to the SCR Catalyst.