P1406 FORD DPFE Sensor Circuit Downstream Hose

Possible causes
– Faulty Differential Pressure Feedback Electronic (DPFE) sensor
– Differential Pressure Feedback Electronic (DPFE) sensor harness is open or shorted
– Differential Pressure Feedback Electronic (DPFE) sensor circuit poor electrical connection
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1406 FORD Description
The purpose of the Exhaust Gas Recirculation (EGR) system on your engine is to limit oxides of nitrogen (NOx) emissions. This is done by redirecting small amounts of exhaust gas back through the upper intake to get mixed in with the air/fuel charge. The resultant diluted air/fuel mixture (i.e., less oxygen per cubic foot) burns cooler and combustion chamber temperatures are reduced accordingly, thereby lowering NOx emissions.

The Ford DPFE/EGR system is controlled by the Powertrain Control Module (PCM). The system employs an EGR Valve, an Electronic Vacuum Regulator (EVR), and a Delta Pressure Feedback EGR sensor (DPFE).

The DPFE Sensor measures EGR flow across an orifice located inside the special EGR Tube. The orifice is positioned between two hose ports coming off the tube which are connected to the DPFE sensor with special heat-resistant hoses. When the EGR Valve is open, a pressure differential is created across the orifice (intake manifold pressure vs. exhaust pressure). By design, this difference in pressure is measured by the DPFE sensor in terms of voltage. The DPFE voltage signal output to the PCM is directly proportional to the flow of exhaust gas entering the intake manifold.

FORD Technical Service Bulletins for P1406 code
2003 FORD CROWN VICTORIA ELECTRICAL SYSTEM
2002 FORD EXPLORER UNKNOWN OR OTHER
1999 FORD E-150 UNKNOWN OR OTHER
1999 FORD E-250 UNKNOWN OR OTHER
1999 FORD E-150 UNKNOWN OR OTHER
1999 FORD E-250 UNKNOWN OR OTHER
1999 FORD E SERIES UNKNOWN OR OTHER
1999 FORD E-150 UNKNOWN OR OTHER
1999 FORD E-250 UNKNOWN OR OTHER
1999 FORD ECONOLINE UNKNOWN OR OTHER