I have a 1997 Ford E250 5.4L Automatic. I have a p0402 I can not get rid of. I have replaced the DPFE three times, EGR Valve and the EGR silenoid. I have pulled the manifold and cleaned all the ports and checked for vacuum leaks, loose hoses.... Today I have vacuum tested the EGR and checked the system pressure and checked volts and ohms all test out. I can reset the code and it will come back in only a few miles. Any Ideas?????? Mike
Monitor the output voltage from the Delta Pressure Feedback (DPFE) sensor. Normal range for the original metal style is 0.4v to 0.65v, and 0.4 to 1.2 for the plastic replacement sensor. Replace the sensor if out of range.
I have replaced the DPFE 3 times 2 of them were in the same week none fixed the problem. I have been using the Haynes manual as a guide and the voltages check out. The EGR tube is clear and on tight also all the gaskets are new. I ran a vacuum on the EGR valve and held it open the tube got hot and the idle was rough so I can assume it is not plugged and the valve is moving freely.
Are you sure the the wires in your connector are good? a 402 is only set by a bad DPFE or a wiring issue
23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
The voltages all are with in range the DPFE and the silenoid? If the voltage is good the wires should be good? What is the chance it is in the ECM? Can the ECM be reprogramed?
Its not to likely its the pcm. I have known of high millage catalytic converters that were partially restricted to do this. It a long shot.