1999 F 150 4.6 LTR. Engine code PO1401. Changed out DPFE Sensor. Cleared that code, but a new code came on. PO401 EGR? Tested for vacuum leaks. Hold at 23in. no jumping around on gauge. Checked for vacuum on green vacuum line from vacuum port and no vacuum on green line. Pull vacuum on EGR valve, seem to hold. Now the new DPFE Sensor I installed has the ref leg and the other leg melted. I have high pressure tubing on the ports coming from the exhaust tube, but the plastic lines from the sensor has melted. Advise please.
Thanks

 

That sensor is supposed to measure only differential pressure. Check EGR valve assy mtg and intake for carbon build up. Hot exhaust should not be getting to the DPFE.