For a complete wiring diagram Refer to Section 8WThe Diesel particulate filter is an inline canister filter located in the exhaust system between the engine and the muffler. This filter captures and stores ash particles created by the diesel combustion process. This filter is monitored by the ECM with a Differential Pressure Sensor. This sensor measures the difference in exhaust system pressure before and after the particulate filter through tube connections directly to the exhaust pipe. As ash and soot accumulate in the filter, the exhaust pressure at the inlet side of the filter increases as compared to the pressure at the outlet side of the filter. When Monitored:With the engine running.Set Condition:The Differential Pressure Sensor signal indicates partial clogging of the particulate filter due to the accumulation of ash or other debris.Possible CausesDAMAGED EXHAUST SYSTEMLEAKING EXHAUST SYSTEMHIGH RESISTANCE IN EXHAUST DIFFERENTIAL PRESSURE SENSOR CIRCUITSHOSE/TUBE CONNECTIONS TO THE EXHAUST DIFFERENTIAL PRESSURE SENSOREXHAUST DIFFERENTIAL PRESSURE SENSORDIESEL PARTICULATE FILTERAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding.(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)1. CHECKING FOR OTHER DTC'SThis DTC can be set when vehicle is driven only on short trips where exhaust and engine temperatures do not reach operating temperature for 30 minutes or more.Turn the ignition on.With the scan tool, read the ECM DTC's.Are there other DTC's set in the ECM?YesRepair other DTC's before continuing with this test.Perform ECM Verification Test Ver. 1.(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)NoGo To 22. VISUAL INSPECTIONTurn the ignition off.Visually inspect the Exhaust Differential Pressure Sensor for physical damage, proper electrical connection and proper mechanical connection. Ensure any tubes and/or hoses connected to the sensor are in good working condition and properly connected at all ends.Visually inspect the entire exhaust system for bent, crushed or otherwise damaged tubes which may cause an exhaust system restriction. Inspect the exhaust system for exhaust leaks.Were any problems found?YesRepair or replace as necessary.NoGo To 33. PARTICULATE FILTER REGENERATIONStart and idle the engine.With the scan tool, Clear DTCs in the Engine Control Module (ECM).With the scan tool, perform the Diesel Particulate Filter Regeneration procedure.After this procedure is complete, turn the ignition off for 60 seconds.Test drive the vehicle.With the scan tool, Read DTCs in the Engine Control Module (ECM).Is the status Active for this DTC?YesGo To 4NoTest complete.4. EXHAUST DIFFERENTIAL PRESSURE SENSOR CIRCUIT HIGH RESISTANCE

Turn the ignition off.Disconnect the Exhaust Differential Pressure Sensor harness connector.Disconnect the ECM harness connectors.Measure the resistance of each Exhaust Differential Pressure Sensor circuit between the Exhaust Differential Pressure Sensor harness connector and the ECM harness connector.Is the resistance below 10.0 ohms for each circuit?YesGo To 5NoRepair the circuit(s) that measured above 10.0 ohms for high resistance.(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)5. EXHAUST DIFFERENTIAL PRESSURE SENSORReplace the Exhaust Differential Pressure Sensor.Turn the ignition on.With the scan tool, Clear DTCs in the Engine Control Module (ECM).Test drive the vehicleWith the scan tool, Read DTCs in the Engine Control Module (ECM).Is the status Active for this DTC?YesReplace the Diesel Particulate Filter.NoTest Complete.