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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 05-09-2008
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Running a P0401

When to advance today, they pulled the code P0401, Exhaust Gas Recirculation Flow Insufficent.

Not more then 10 months ago I had a P0402 code and replaced the DPFE sensor which did the trick.

Anybody know whats wrong?
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Old 05-29-2008
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If i remember right the code pulled 10 months ago was a Po402, which i did replace the DPFE sensor, if i remember correctly, the code read ExcessiveFlow or something, would this still be affected by my DPFE, if so couldnt I just clean it and with what?

Last edited by Trigger; 05-29-2008 at 12:49 AM.
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Old 05-29-2008
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P0401 and P0402 are usually caused by incorrect DPFE voltage to the PCM. Sometimes the DPFE is permanently damaged, sometimes it just has condensation inside. I would try a quick fix by removing it, shaking out the water and letting it dry overnight with the hoses off and the DPFE ports facing down.

DPFE's live in the harsh environment of the exhaust gas stream. The OE part doesn't last forever. Some of the aftermarket parts seem to be even less durable.
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Old 05-29-2008
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Make sure the hoses are clean
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Old 06-03-2008
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I tried cleaning it, there was moisture in the hoses, so i took of the sensor for the night but after i hooked it all back together the check engine light came on again after a couple miles, any other suggestions? Also, i hear that you should replace the egr along with the dpfe which im thinking about doing, what does the egr look like and where is it located on a 4.0?

Last edited by Trigger; 06-03-2008 at 01:06 AM. Reason: added stuff
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Old 06-03-2008
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Quote:
Originally Posted by Trigger View Post
I tried cleaning it, there was moisture in the hoses, so i took of the sensor for the night but after i hooked it all back together the check engine light came on again after a couple miles, any other suggestions? Also, i hear that you should replace the egr along with the dpfe which im thinking about doing, what does the egr look like and where is it located on a 4.0?
I wouldn't waste the money. A code P0401 or P0402 is 1000x more likely to be caused by the DPFE than the EGR valve itself. IMO, it is better to replace the DPFE with genuine Ford, not aftermarket.
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Old 06-04-2008
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I agree with you on replacing the part with a ford part, but, that costs a lot more usually. I think im just gonna have to buy another cheap dpfe from checkers haha. This last one lasted about 9 months.
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Old 06-04-2008
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Tousley ford in Minn You found them via SVT performance . com

(10% over dealer cost)

Rich
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Old 06-05-2008
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Rich, can they send the parts to my address?

And you guys dont think i should change the EGR, being that I just changed the DPFE last fall, and I heard from searching this forum that people say when the DPFE goes bad the EGR is also probably bad.

EDIT*

Just took off the sensor again when i got home, there was again moisture in it, Now i dont know but this morning the check engine light went off by itself, then about 7 hours later next time i drove, it popped up again, is there anyway to stop the moisture buildup?

Last edited by Trigger; 06-06-2008 at 12:29 AM.
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Old 06-09-2008
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Trigger, Mines doing the same thing. I've replaced the DPFE 4 times in the last 2 years. Replaced the Hoses also. Still every time the 401 pops up the DPFE and hoses are wet. I'm replacing the whole upper intake to a composite. They have NO egr system at all.
Therefore NO DPFE to mess with. I'm still trying to found out how to lose the CEL now since I have NO egr. My PCM is still for an '01 and is trying to read a signal for the egr. Should have the '04 Upper on in a couple of weeks. Hopefully by then I'll have the answers.
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Old 06-09-2008
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...I heard from searching this forum that people say when the DPFE goes bad the EGR is also probably bad.
Total nonsense. One controls the flow, the other measures it. They could fail independently or together but one does not cause the other. EGR valves rarely fail anymore, DPFE's do regularly.


Quote:
Originally Posted by Trigger View Post
Just took off the sensor again when i got home, there was again moisture in it, Now i dont know but this morning the check engine light went off by itself, then about 7 hours later next time i drove, it popped up again, is there anyway to stop the moisture buildup?
You can't stop moisture from forming in the exhaust because H2O is one of the two major products of combustion of any hydrocarbon fuel.
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Old 06-12-2008
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What about the gas you use, I do know that after I started going to a different gas station regularly thats when the code started.
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Old 06-18-2008
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Since I believe that the check engine light is caused by the moisture buildup, would changing the dpfe even do anything then?
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Old 06-18-2008
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What about the gas you use, I do know that after I started going to a different gas station regularly thats when the code started.
I can't see it making much difference. Your engine should be exhausting a comparable amount of H2O, regardless of the gasoline source.


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Since I believe that the check engine light is caused by the moisture buildup, would changing the dpfe even do anything then?
The DPFE lives in an exhaust stream that contains a large percentage of H20. You cannot eliminate the water condensation, so the DPFE has to deal with it.
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Old 06-18-2008
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So do you think the code may be due to something else besides the dpfe?

Thanks bob
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Old 06-18-2008
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Could be:

dry-rotted hoses TO the DPFE

corroded or perforated EGR tubes that the DPFE hoses connect to


Personally, my tack is to buy the DPFE at AutoZone, keep the receipt. When the code comes back in 4 months or so, have them read out the code and use their 2 year Warranty.

Carquest only warranteed it for one year, one time free replacement, which I used. We'll see how good AutoZone honors their warranty when this one (#4 including original) goes south on me. It was a Tomco brand. http://www.tomco-inc.com/EGR_Delta_P...nsor_9066.aspx
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Old 06-21-2008
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All the tubes look fine, and since theres moisture in the tubes up to the DPFE and also in the DPFE, I wouldnt think its the DPFE's fault, Could it be an O2 sensor, or even the EGR?
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