What does it mean when the SCR light is on?

[LaDaniel]

When the SCR light is on, it indicates a fault in the Selective Catalytic Reduction system. The following are the possible causes: 1. Sensor damage; 2. Poor connection of the sensor plug; 3. Short circuit or related wiring harness failure. The principle of the Selective Catalytic Reduction system: Under the action of a catalyst, the reducing agent NH3 selectively reduces NO and NO2 to N2 at temperatures between 290 and 400 degrees, with almost no oxidation reaction between NH3 and O2, thereby improving the selectivity of N2 and reducing the consumption of NH3. The Selective Catalytic Reduction system consists of an ammonia supply system, ammonia gas, air injection system, catalytic reaction system, and control system. To avoid energy consumption from reheating the flue gas, the SCR reactor is generally placed after the economizer and before the air preheater, i.e., in the high-dust section. Ammonia gas is added to the horizontal pipeline before the air preheater and mixed with the flue gas.