Check engine codes P0401 and P0402 solution | Ford Explorer Forums - Serious Explorations

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Check engine codes P0401 and P0402 solution


New Member
November 23, 2010
Reaction score
City, State
Tampa, FL
Year, Model & Trim Level
2001 Explorer Sport
Hey Folks,

I just registered on this forum and I wanted to post a thread in relation to some of my recent issues. I got a lot of excellent information on here and I wanted to return the favor.

For the past 6 months or so, my check engine light has been on. I initially got a code of P0402 (EGR flow excessive). Finally, after reviewing many threads and posts on here, I decided to get this nagging problem fixed. When I went to Autozone to check the code one last time before taking my first step toward fixing it, I got a new code. This code was P0401 (EGR flow insufficient, I think?). Well, I decided to first try replacing the DPFE sensor. This is known as EGR valve sensor at Autozone. The sensor was $22 and took all of 3 minutes to replace. This was 5 days ago and no check engine light. Looks like it was just a faulty sensor.

Thanks again to everyone on here who posted their experiences with this issue. It helped me out a lot and I hope this thread helps someone else.

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i have the same problem two i have a check engine light on for p401 i change dpfe sensor i even put new lines to dpfe to exhaust lines the only check engine light i have it run perfect

Did you change the DPFE sensor first? Or do the EGR valve work?

Its the carbon build up.. I replaced my DPFE sensor, replaced EGR valve and sensor and still the light stayed on.. So after throwing parts in it, I brought it down to my friends shop and he informed me that it is the carbon build up and just needs to be cleaned out.. I guess there are 2 little holes that get clogged up and its very common... He told me its time consuming so im gonna have him do it since its still cold here in New England and im tired of this CEL and all the money ive thrown at this problem with no success

That true.
On another Ford engine, I didn't even know that where supposed to be holes in there, I just decided to clean that carbon build up because I did "open" that for some other reason and... surprise! Fixed that code too.

Would it be hard to do myself bro? I have the day off so if I can save a buck here let me know. Ill get my tools ready, just give me the word and hopefully some insight!!