Detroit GHG17 engine Parked SCR Efficiency Test validates Selective Catalytic Reduction (SCR) system integrity from engine warm-up through NOx efficiency.
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You would normally run this test to detect:
SCR catalyst efficiency concerns
DEF concentration concerns
NOTICE
The total time for the test is between 60 and 85 minutes.
Note : The engine must be at operating temperature for accurate results (Coolant temperature greater than 71°C (160°F).
This routine will bring the engine operating temperature and aftertreatment temperatures up to enable dosing conditions where NOx conversion efficiency can be verified.
Before starting the routine, if the DPF lamp is illuminated, run a parked regeneration.
To run the Parked SCR Efficiency test:
1 Go to the SCR System tab in the Service Routines window.
2 Select Perform Parked SCR Efficiency Test from the drop-down menu.
3 Press the Start button.
A CAUTION dialog box will be displayed:
4 Ensure the transmission is in park or neutral and the parking brake is applied; press Yes to continue or No to exit.
5 Hold DPF Switch to the ON position for five seconds and then release (engine speed will increase indicating the routine has started).
6 The test will be carried out with the current status shown in the progress box:
NOTE: If the test aborts at any point, the progress box will show a description of where the test has failed in the cycle.
The test is not a passed or failed test; the progress box will show the status “nox concentration not high enough” at the end of the test, after one hour of stabilizing.
NOTICE: If the progress box shows the status “routine not started” or “stopping the routine,” please check the following:
- High idle safety conditions: Park brake, neutral switch, clutch state, vehicle speed, engine idle states. Please set them as requested in the service document.
- Check for the component failure codes in the SCR system (DEF pump and DEF doser valve faults not active) and troubleshoot them first.
- After performing (a) & (b), if the routine still doesn’t run, then perform an ignition cycle and make sure the communication from all the modules is disabled before turning the ignition ON again and starting the routine.
- After performing (c), if the routine still doesn’t run, then complete a parked regeneration before starting the routine.
NOTICE: If 520372/16 – SCR closed loop at maximum limit fault is active/ confirmed ( and not “permanent”) and if any of the following codes below are not active/ confirmed , run a parked regen and idle the system for 30 minutes then cycle the ignition before starting the service routine
More repair cases for Detroit Diesel engines,please refer to:Detroit Diesel Engine Repair