I have a 1997 Ranger V-6, 4.0L with the check engine light illuminated. I had Auto-zone to check codes, P0401 and P0402 came up. One code states there is insufficient flow to the EGR system, the other states there is excessive flow to the EGR system. Do I need a new EGR valve, or a new DPFE sensor? How do I know which may be culprit. Called Ford dealership and all they could tell me was that they would have to hook it up to their computers. I would like to avoid expensive diagnostic charge and fix it myself. Any help would be appreciated.
When I ended up replacing the dpfe for the p0401 code, the old dpfe was gummed up at the inlet and outlet. Pull the tubes off of the sensor and look at the stems. That should give you a pretty good idea whether or not it's the culprit.
Thanks to all who replied to my question. It was the DPFE sensor. It was gummed up and corroded. I replaced it (15 min tops!) I have been driving for a week.....no check engine light. You guys saved me some bucks! Thanks.
FYI to anyone with the same problem. It also is called a EGR valve sensor at some parts stores. Ford wanted $76.00 dollars, I found it at a local parts store for $46.99. It pays to shop around.