Circuit DescriptionThe engine aftertreatment system monitors the soot load in the aftertreatment diesel particulate filter. Under normal operating conditions, the aftertreatment diesel particulate filter is self-cleaning, where soot is converted to carbon dioxide, nitrogen, and water. Under light load operating conditions, it can be necessary to perform a stationary regeneration of the aftertreatment diesel particulate filter. The soot load in the aftertreatment diesel particulate filter is estimated, using the aftertreatment differential pressure sensor and the calculated soot output of the engine.

Component LocationThe aftertreatment diesel particulate filter differential pressure sensor is mounted on the diesel particulate filter. It is a combination sensor that detects both diesel particulate filter differential pressure and outlet pressure. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the DiagnosticsThis diagnostic only runs after successful completion of an active regeneration of the aftertreatment diesel particulate filter.

Conditions for Setting the Fault CodesThe estimated soot load in the aftertreatment diesel particulate filter was higher than a calibratible value.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkPossible causes of this fault code include:

A malfunctioning aftertreatment fuel injectorMalfunctioning aftertreatment temperature sensorsA malfunctioning aftertreatment diesel oxidation catalystA malfunctioning or stuck in-range aftertreatment diesel particulate filter differential pressure sensorAn engine malfunction resulting in high engine out smokeA damaged or malfunctioning OEM wiring harness to the differential pressure sensor.

Possible Cause:1) Aftertreatment DPF differential pressure sensor failure2) Fuel rail pressure relief valve failure3) Loose injector high pressure connector(s)4) Aftertreatment DPF failure5) ECM calibration