I have a '99 EX with the 6 cyl OHV motor. I found the HIGH port on the dpfe sensor was melted and the hose that connected to it was severely cracked. I replaced the sensor and hose but would like to know the root cause of the problem. Any suggestions?
In normal operation there is no gasses traveling through the tubes. This device measures deferential of pressure. But as you stated the hose had cracks (leaks) This aloud the hot gasses from the Exhaust to flow through the hose to the DPFE sensor melting it. A clogged line would not melt the sensor but would make it inoperable.
Witten by wildbill a person that worked for the company that designed and manufactured the sensor for Ford Motor Corporation.
Exhaust stream does not pass through this transducer(DPFE) the pressure applied to the sensor is a dead head so the thermal transfer is contained to the stagnant air trapped in the hoses to the sensor that is very slow to transfer heat.
The plastic housing was to reduce cost of this transducer(DPFE) not to dissipate heat in fact the plastic transducer would melt with pressure leaks.