Hey guys names josh I have an 02 F150 with the 4.2 V6 and it runs great but I need to put it through emmissions and its showing the service engine soon light!!! Over the course of the past couple of years I've replaced verything in the egr system egr Valve, EVR soleniod, DPFE sensor, I started with the dpfe sensor because it was showing all 3 generic EGR codes 0400,0401,0402, and they whent away then about a month later it threw the light again and gave me this code P1400 Low voltage input on DPFE Circuit!! At this point I whent to JUst answer .com and talked to a ford Mechanic with 25Years plus experience and I asked him if I could just run a Jumper wire from the ground wire on the sensor to the negative terminal on the trucks battery for testing purposes!! The reason I asked him this was because I have a fairly good understanding of electricity and knew that if I Just tried it I could potenshally damage my ECM!!! He said it was fine that a ground is a ground regardless and to just go ahead and overlay the wire to the battery!! That seemed to work for a while but now I'm back to Sqaure one!! The same code P1400 Dpfe circuit low voltage input!! Does this ground have to go back to the ECM or is this fine!!! The truck only has a little over 50,000 easy miles on it!! And it runs great other than this stupid service engine light!!!