P1401 MAZDA DPFE Sensor Circuit High

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)
P1401 MAZDA 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 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.

MAZDA Technical Service Bulletins for P1401 code
2001 MAZDA TRIBUTE ENGINE AND ENGINE COOLING:ENGINE
2002 MAZDA TRIBUTE ENGINE AND ENGINE COOLING:ENGINE
2001 MAZDA B4000 ENGINE AND ENGINE COOLING:ENGINE
2002 MAZDA B4000 ENGINE AND ENGINE COOLING:ENGINE
2001 MAZDA TRIBUTE ELECTRICAL SYSTEM
2002 MAZDA TRIBUTE ELECTRICAL SYSTEM
2001 MAZDA B4000 ELECTRICAL SYSTEM
2002 MAZDA B4000 ELECTRICAL SYSTEM
2001 MAZDA TRIBUTE ENGINE AND ENGINE COOLING:ENGINE
2002 MAZDA TRIBUTE ENGINE AND ENGINE COOLING:ENGINE