Trying to troubleshoot another Ford EGR problem. Can anyone give me advice on how to narrow it down before I spend a fortune throwing parts at it?

http://engine-codes.com/p0401_ford.html
http://www.obd-codes.com/p0401

Most of the time it's the DPFE that's faulty you can easily check the egr valve with a hand operated vacuum pump if the engine almost stalls or does stall when the valve is open the egr passages are clear and working fine. If you have access to a scan tool that shows DPFE voltage see if it changes when you open the egr valve. Dealers usually keep the DPFE sensor in stock. If an egr system is operating properly opening the valve should make a noticeable difference in the way it runs, that will help eliminate bad valve or clogged passages.

Brian Russell said:

Trying to troubleshoot another Ford EGR problem. Can anyone give me advice on how to narrow it down before I spend a fortune throwing parts at it?

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Did you find a solution to this? My 2008 Sport Trac also started throwing the P0401 code. I ordered the EGR valve but I haven't replaced it yet. I was thinking it may one of the vaccum lines.

Don't you hate it when the OP doesn't come back to post the solution to the problem.

I have seen a lot of the DPFE lines burn out, but that was a bit older than 08... be worth a look.

DPFE sensor. Its one of the only things left that literally needs no diagnostics any more.

blacksnapon said:

DPFE sensor. Its one of the only things left that literally needs no diagnostics any more.

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I tried to find the DPFE sensor on the motorcraft site and it looks like the 2008 model doesn't have any. I also couldn't find any references to just the DPFE sensor on any of the usual places like autozone, oreillyauto, etc. The only reference I see is the EGR valve which I have already ordered. Before I replace the EGR valve though, I was hoping there might be some other things I should check! Thanks for the tip for the DPFE but I haven't found one on my vehicle and that was the first thing I considered... until I couldn't find any reference to it on my truck!

Bumblebrow said:

I tried to find the DPFE sensor on the motorcraft site and it looks like the 2008 model doesn't have any. I also couldn't find any references to just the DPFE sensor on any of the usual places like autozone, oreillyauto, etc. The only reference I see is the EGR valve which I have already ordered. Before I replace the EGR valve though, I was hoping there might be some other things I should check! Thanks for the tip for the DPFE but I haven't found one on my vehicle and that was the first thing I considered... until I couldn't find any reference to it on my truck!

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So I ended up spending 20 minutes to replace the EGR valve and luckily, I reset the errors using Torque on Android, and now I'm all fixed up!

Well, partly, no more CEL but I noticed one of my O2 sensors is in bad shape! Does anyone know which O2 sensor is bank 4 sensor 2? I looked on Chilton, MotorCraft/Fordparts but they don't mark them in the diagram for which bank/sensor it is!

It'll either be bank 1 or bank 2 .bank 1 is pass side, bank 2 is driver side. sensor 2 is after the catalytic converter. They're also known as a catalyst monitor.