Since I got a notice that there was a reply, I figured I would update my situation.


I replaced the DPFE. Still got the P0401, and rough idle & missing.

I replaced the EGR. Still got the P0401, and rough idle & missing.

I took off the throttle body an cleaned out copious quntities of carbon. It was amazing how much was there.

So, then it runs great, for a while, no codes. Then back to the same ole rough idle & missing. This time, a new code.

I dont remember the number but it was "cylinder 1 misfire".

So, I replace the coil pack on cylinder 1 and ta-da, runs like a champion.

Then about a week later, I start getting thr P0401 AGAIN!!!!

It's running fine, so I just ignore it. I consider the CEL is just a dashboard decoration now.

Ive done everything but replace all the vacuum hoses. I guess I will try that next. When I have time.

 

I bought a DPFE sensor at O'Reilly's for $55. I went to replace it on the truck but I can't find it. I went back to O'Reilly's and they couldn't find it either. According to the Hanes Manual it's supposed to be right near the EGR valve, but there isn't anything there and no unplugged vacuum lines either.

Is it possible that this truck doesn't have a DPFE sensor?

Does anyone have a picture of it or where it is supposed to be?

Thank you,

 

I don't know what year they went to the all in one, but if your looks like this, it has to be replaced as a unit like I had to do on my 05 Explorer.

 

I have read all the replies and see there is still a lot of confusion and miss information.
The vendors other than FORD have incorrect information in their data bases for discription of this sensor.
It is not a position sensor, it is as the name implies a pressure sensor.
It reports back to the PCM the results of a system test.
On 97 thru 03 it is mounted stand alone just below the master cylinder power brake vacuum drum.
The code 401/1401 does not tell you this sensor is faulty unless testing determines that is all that is left assuming tests of the system finds no other isues.
Next, do not use a DPFE other than a Ford unit. Reason is the tolerence of the test is very tight such that the aftermarket unit may not be good enough to function correctly in this system application.
Exhaust is drawn/forced thru the metal tube that has a disc with a small hole. The DPFE measures the pressure drop accross the disc.
When the PCM operates the EGR by a controlled amount, the DPFE "expects" to see a certain pressure within narrow limits. If to low, the 401/1401 code is set.
So, you need to be sure by test and inspection that the flow can take place when requested.
The EGR is operated by a vacuum supply gated through the electrical control valve.
Bottom line is that any part of the system that has an issue will cause the test failure as well as a bad sensor that tries to report the test results.
Last, this test is done two times before a failure is reported.
If the EGR is locked out from a detected test failure, fuel mileage suffers to some degree even through you may not feel a drivability difference.
The reason the system is there and so touchy is an EPA mandate.
It allows exhaust back into the intake to limit combustion temperatures that reduces NX emissions.
When the EGR is called to operate, the ignition is advanced, the fuel is cut back, so there is more to this than you know about and not there just to be extra complicated.
Good luck.

 

I talked to Airtex directly more than a year ago. They claim their Pressure Feedback Sensor will do exactly what it suppose to do, way better than there older units. Get one on Rock Auto.com

 

Wow Ben........similar to my 97 4.6L
i had a P0118 so i replaced the coolant temperature sensor. cleared that code.
a P0304 cylinder 4 misfire. i ran some fuel injector cleaner thru it after plugs and wires didnt fix it. that code is gone.
and the P0401 insufficient EGR flow. i pulled the throttle body off and cleaned the egr ports. i noticed the egr tube was broken away from the manifold. i put some magic putty on it to seal it up. reattached the battery and all codes were gone. drove it for awhile and it ran absolutely terrible. the CEL came back on and it ran the same as it did before i started everything. which was halfway decent. now its showing codes P0401 again and now a P0301. cylinder 1 misfire..... how could i go from a cylinder 4 to a cylinder 1 misfire?are both those cylinders run off the same coil? i noticed a crack on one side of one of the coil packs. maybe its getting wet inside like a distributor?
i cant leave my CEL as decoration since my inspection is due! and now we just got 3 feet of snow in 24 hours here in buffalo! fun wow!

I replaced the DPFE. Still got the P0401, and rough idle & missing.
I replaced the EGR. Still got the P0401, and rough idle & missing.
I took off the throttle body an cleaned out copious quntities of carbon. It was amazing how much was there.
So, then it runs great, for a while, no codes. Then back to the same ole rough idle & missing. This time, a new code.
I dont remember the number but it was "cylinder 1 misfire".
So, I replace the coil pack on cylinder 1 and ta-da, runs like a champion.
Then about a week later, I start getting thr P0401 AGAIN!!!!
It's running fine, so I just ignore it. I consider the CEL is just a dashboard decoration now.
Ive done everything but replace all the vacuum hoses. I guess I will try that next. When I have time.[/quote]

 

On 97 thru 03 it is mounted stand alone just below the master cylinder power brake vacuum drum.
I have a 2001 F150 4.2L V-6 A/T.
The DPFE on this engine is mounted stand-alone fashion up high on the right side of the engine, up top toward the front about 6" from the EGR. It has a wiring harness plugged into it coming from the centerline. Below it are 2 thick rubber hoses in parallel connecting the 2 vacuum ports on the DPFE to the stainless steel tubing connected to a stainless steel tube coming from the exhaust manifold below. This lower stainless steel tubing connects to the bottom of the EGR itself.
Picture with labels follows here:
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It is extremely easy to remove and replace. My local Ford dealer wanted $63 for the current version, Autozone wanted $36 for their version.
Added 22 Jan 2012: On my model, it takes all of 5 minutes to replace its DPFE, it is extremely easy to do. Dealers will charge their victims $75 and up to do this extremely simple job.

 

YouTube - P0401 EGR Insufficient flow test
Using computerized testing equipment on a 2004 Ford Focus, but applies here also.

 

Thanks to this forum, I was able to locate the part. Instead of looking for DPFE sensor, look for EGR Position Sensor or EGR Pressure Feedback Sensor. Apparently, "D" stands for EGR at the parts counter.

Still don't know if this will clear my code, but at least I don't have to go dealer-only to get the part due to terminology.



-1999 F-150 Lariat, 5.4 Triton, dual Flowmasters and K&N air filter.

 

Well, you see after market vendors either have it wrong in their data base or discribed incorrectly.
Here is the difference between the two.
The DPFE is short for Differencial Pressure.
Position Sensor is actually a detection of movement.
The two are very different in application and system use.
.
The DPFE came into use after 1996 to about 2003.
After 2003 there were some vairations of it in design and mounting.
The PS type was used mostly from 1985 to 1996 and was often mounted directly on the EGR to detect the EGR diaphram movement.
On different models through the years different versions of the pressure sensors were used as well as their mounting positions moved.
Some were exhaust pressure sensors as well.
From 2004 on they are different again very often.
Parts stores usually do not know the above info so you can ask correctly and they still don't know what you are asking for.
A good way is to have them get the visual display up on screen and point it out to them for your year and engine.
.
There are people who make up these information systems that have no knowlege of the parts, how they work, when or what they were used on so you get the "benift" of errors and miss information that likely will never be corrected in their data bases.
Case in point, try fitting a right side cat replacement from Walker on a 97 to 2003 truck. The rear cat is not rotated correctly so the OX sensor will fit in as intended. Nothing wrong with the cats but you can't use the assembly as built even though it bolts up.
How long this has been going on or when they will correct it is anybodies guess.
The solution is to mount the assembly then have a muffler shop cut the rear cat, rotate it and re-weld it in place leak free, then your good to go. Of course then your warrenty is no good for a part that was not assembled correctly to begin with.
An OEM unit cost $1700+ vs about $300 +/- so you take your pick how you want to handle it on an older truck..
The cat info above is unrelated to the EGR but included as an example of after market parts issues you can get into.
Said another way, everything is not always perfect.
Good luck.

 

as noted above...the throttle body "adaptor".....

 

However, EGR VALVES DO FAIL. Mine did, and caused my 2001 F150 4.2L V6 to throw its P0401 code. I wasted a lot of time approaching the problem, as I assumed the common knowledge that EGR valves 'very seldom fail.' After disassembling my intake manifold plenum to clean out the EGR passages, I removed my 10 year old EGR valve & found it completely clogged and utterly non-functional. Could have saved myself a great deal of effort had I removed and inspected the EGR valve FIRST, rather than much later.
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Usually EGR valves are the easiest parts of the P0401 code protocol to check. If you know what you're doing, CHECK EGR Valve first. Replace it only if proven defective. After I cleaned the gunk out of my old valve, it appeared to be working -- applying vacuum to its vacuum port I was able to see the valve opening & closing - you can only see directly this after removing the EGR valve from your engine. I replaced it anyway after all the trouble it had caused me.

 

i got one from NAPA auto parts for 96 bucks and then i saw one on ebay for an Explorer and an f-150

 

32000 plus hits on this thread.
The code started out as a 1401 involving the DPFE communications with the PCM then turned into a 401 low flow code.
If replaceing the DPFE use only a Ford part.
Next, test for system blockage before taking anything apart.
Pull just enough vacuum on the EGR to open it.
If the tract through the EGR and into the intake is open the motor will idle rough or stall when testing at engine idle.
If no roughness, there is an issue. The DPFE is not part of this test so you have a seperation of logic as to what is or is not the trouble area.
The EGR system is not that complicated but must be understood how it works or a hassle developes on a system with only several parts and hoses.

 

auto zone normal answers i get from them