OBD Operation Summary for 6.7L Diesel - MotorCraftService.com

OXIDES OF NITROGREN (NOx) CONVERTING CATALYST MONITORINGSelective Catalyst Reduction Catalyst Efficiency MonitorThe SCR catalyst is monitored to ensure it is capable of NOx conversion. The concentration of NOx upstream ofthe SCR is calculated based on a model. NOx concentration downstream of the SCR is measured with a NOxsensor. Using these concentrations, the cumulative efficiency of the SCR catalyst is calculated and compared to athreshold. If the cumulative efficiency is below this threshold for a sufficient period of time, a fault will be indicated.The reductant, Diesel Exhaust Fluid (DEF), which is used as part of the SCR catalyst reaction, is monitored toensure the tank is not refilled with an improper reductant. Upon detection of a refill event, the monitor is activated.After the SCR Catalyst Efficiency Monitor has completed and the SCR has been determined to be functional, theefficiency monitor continues to calculate the cumulative efficiency of the system. Each subsequent value forcumulative efficiency is included in two filtering routines, one for short term efficiency and the other for long termefficiency. If the difference between the two filtered efficiencies becomes greater than a threshold, a fault isindicated. the short term efficiency needs to be less than 0.20 and the delta between short and long term efficiencyneeds to be greater than 0.10.Monitor Summary:DTCsMonitor executionMonitor SequenceP20EE – SCR NOx Catalyst Efficiency Below ThresholdP207F – Reductant Quality PerformanceP20EE - Once per driving cycleP207F – After detection of a Diesel Exhaust Fluid refillP20EE test followed by P207F testSensors OK NOx, EGT12, EGT13, ECT, DEF injection system, MAF, BP, O2,DPFP, EGR systemMonitoring DurationP20EE – 2 Minutes, P207F – Dependent on driving conditionsFORD MOTOR COMPANY REVISION DATE: FEBRUARY 9, 2012 09.01.00.02-PAGE 15 OF 157