Theory Of Operation

The Diesel Particulate Filter is an in-line canister filter located in the exhaust system between the engine and the SCR Catalyst. This filter captures and stores soot particles created by the diesel combustion process. 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. This filter is monitored by the PCM with a Differential Pressure Sensor. There is a tube at the inlet and outlet of the Diesel Particulate Filter. A hose is attached to each tube. The other end of the hose is connected to the Differential Pressure Sensor. The Differential Pressure Sensor compares the pressure at the Mass Air Flow Sensor to the pressure at the differential pressure sensor. When this comparison exceeds a calibrated amount for a pre-determined amount of time, this DTC will set.