DPFE - EGR tubes
 

Hi gents. I just purchased a 99 F250 with the V10 and I am having smog code issues. I pulled a Code of P1406 which is a DPFE sensor fault. I found a thread here on how to do a voltage test on the sensor and it tests out perfectly. In inspecting the 2 hoses that go to the EGR tube, the small tube does not allow me to blow through it. The larger one doesn't have any restrictions at all. The hoses are fine so I'm wondering if the small tube is plugged on it's way to the EGR tube. Should I be able to blow through without any resistance on both tubes and could this be my issue with the 1406 fault. Truck has 353,000 miles and runs great but I need to get this fault figured out to pass smog. Any help would be appreciated.

Zoli

For any of you interested in the outcome, here goes. I researched the DPFE stuff and found that the 2 tubes are to measure differential in the EGR system so that told me it needed to be unclogged. The truck has 353,000 miles on it. I tried and tried to clear out the carbon but it was in a tough spot and it was really thick. I cut the tube half way down with a die grinder and I was able to get a drill with a firm wire on it to slowly open up the passage. I reset the error code and hopefully that is that. I will order a new EGR tube to make the fix clean and permanent.

That being said, when I test drove the truck, there was a shudder in the engine at low rpms with low acceleration in drive and OD. I researched that issue and found that I needed to flush the trans and put in Synthetic Mercon V and maybe even a friction modifier to loosen up the clutches in the torque convertor. I was also prepared to change the torque convertor if the flush didn't work. Well after clearing up the DPFE tube, that also fixed the shuddering problem as well. Apparently the RGR valve was not closing on light acceleration and causing the engine to shudder. Winner winner, chicken dinner. Trucks runs fantastic!!!

Thank you for posting the solution.
Well done!