Faulty Reductant Pump and Sensor Assembly
Reductant Pump and Sensor Assembly harness is open or shorted
Reductant Pump and Sensor Assembly circuit poor electrical connection
Faulty Reductant Control Module
Engine Light ON (or Service Engine Soon Warning Light)
The selective catalytic reduction system reduces Oxides of Nitrogen (NOx) emissions by injecting a metered amount of reductant into the exhaust gas stream entering the selective catalytic reduction catalyst. Within the selective catalytic reduction catalyst, the reductant reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the Engine Control Module (ECM) and the Reductant Control Module via serial data. The Reductant Control Module varies the amount of reductant added by varying the reductant injector duty cycle in response to changes in engine-out NOx levels. The Reductant Control Module supplies system voltage to the reductant pump motor. The Reductant Control Module controls the solenoid by grounding the control circuit. The Reductant Control Module can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. The Diagnostic Trouble Code (DTC) will be set when the Reductant Control Module detects a short to voltage in the control circuit.