Circuit DescriptionThe aftertreatment diesel exhaust fluid return valve is controlled by the Engine Control Module (ECM). The return valve position determines where diesel exhaust fluid will flow as it exits the dosing unit. When the return valve is activated, the dosing system will purge and return the diesel exhaust fluid in the lines to the tank. Component LocationThe aftertreatment diesel exhaust fluid return valve is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately. Conditions for Running the DiagnosticsThis diagnostic only runs when the aftertreatment diesel exhaust fluid dosing system is purging. Conditions for...

Circuit DescriptionThe engine control module (ECM) monitors the NOx concentration in the engine’s exhaust gases using an aftertreatment intake NOx sensor and an aftertreatment outlet NOx sensor. By comparing these two values, the ECM is able to determine the conversion efficiency of the SCR catalyst and dosing system. Component LocationThe SCR catalyst is located in the vehicle’s exhaust system, after the diesel particulate filter and decomposition tube. Conditions for Running the DiagnosticsThis diagnostic has to meet specific engine and aftertreatment conditions to run and complete. Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the NOx conversion across...

Circuit DescriptionThe aftertreatment outlet NOx (nitrogen oxides) sensor is a smart device and communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment outlet NOx sensor performs its own internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually. The aftertreatment outlet NOx sensor is used to measure the NOx emissions at the outlet of the aftertreatment system. Component LocationThe aftertreatment outlet NOx sensor location can vary...

Circuit DescriptionThe Engine Control Module (ECM) provides a 5 volt supply and a ground to the aftertreatment diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the ECM on the sensor signal circuit. This sensor signal voltage changes, based on the aftertreatment diesel exhaust fluid pressure supplied by the dosing unit. The ECM will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures. Component LocationThe aftertreatment diesel exhaust fluid pressure sensor is internal to the aftertreatment diesel exhaust fluid dosing unit and can not...

Circuit DescriptionThe aftertreatment intake NOx (nitrogen oxides) sensor is a smart device and communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment intake NOx sensor performs internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually. The aftertreatment intake NOx sensor is used to measure the NOx emissions at the intake of the aftertreatment system. Component LocationThe aftertreatment intake NOx sensor is mounted on the engine...