OBD Operation Summary for 6.7L Diesel - MotorCraftService.com

Typical EGR Flow Check Entry Conditions (Low Flow Detection):Entry Condition Minimum MaximumEngine Torque 100 Nm 600 NmEngine RPM 600 rpm 2500 rpmEngine Coolant Temperature 70 deg C 100 deg CEGR Valve Position 40% 60%EGR Rate Desired Value 0% 100%Typical EGR Flow Rate Malfunction Thresholds:AirCtl_rEGRModMaxDvtFlt > 28 (insufficient flow); AirCtl_rEGRModMinDvtFlt < -22 (excessive flow)EGR Cooler / EGR Cooler Bypass MonitorThe functionality of the EGR cooler system, including the bypass valve, is monitored by means of comparing amodeled EGR temperature downstream of the cooler with a sensor value. Both under-cooling and over-coolingare detected. Monitoring occurs when the engine is in normal operation under closed-loop exhaust gasrecirculation control and no air system errors are present. Common release conditions for both under-coolingand over-cooling include an engine coolant temperature within a calibrated range (60 - 90 deg C). A workingrange of engine speed and torque are calibrated for robust detection of a failed cooler (under-cooling) or a stuckECB valve (over-cooling). If these conditions are met, general monitor release occurs for over-cooling if the ECBvalve is in the open position and under-cooling if the ECB valve is in the closed position. The monitor thenchecks for a steady-state condition using the gradient of the modeled temperature of the EGR downstream of thecooler. The gradient of the modeled temperature is compared to a calibrated threshold to determine steadystate.Once the general release and steady-state conditions are met a timer counts to ensure the conditions areheld for a calibrated time, after which the monitor is released and the modeled value is compared to the sensorvalue for EGR temperature downstream of the cooler. If the difference between the modeled and sensor valueexceeds a threshold calibrated as a function of engine speed and torque then a malfunction is detected.EGR Cooler (Under-cooling) Monitor:DTCsMonitor executionMonitor SequenceMonitoring DurationP2457 – EGR Cooler PerformanceContinuous, once entry conditions are metNone1 second to detected a malfunctionFORD MOTOR COMPANY REVISION DATE: FEBRUARY 9, 2012 09.01.00.02-PAGE 45 OF 157