P0401 DPFE Code

This is my C.E.L. problem over 100000km no warranty 2002 windstar.This doesn't seem to effect my gas mileage. I know this sensor takes the differential pressure of EGR line and that there is a flow. My question is, what does the ECM do with this info & does it adjust anything according to this info?
Thanks
Darren

I'm quoting from the Ford Manual here: "P0401 - EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less then the desired minimum."

If this code is set, the vehicle will not pass an emission test, at least not here in the states. It may take two minutes to change one of these. Finding a replacement sensor is the most complicated part of the job.

I hope this helps. Good luck.

Jim

Thanks Jim, I guest if it won’t pass the emissions test the ECU must be adjusting something. It probably is not running @ max efficiency. So I will change it.
Thanks
Darren

Please Help!!!!! I need some info on how to replace the EGR valve on my 2001 Windstar or a sight that will take me through the process. the emissions people told me that it was the EGR valve or oxygen sensor.

Thanks
Jason

Windstarprob- if you're getting the same code it's most likely the DPFE sensor. A common failure on these vehicles. I replaced mine on my '01 a couple years ago (actually got the dealer to replace it under warranty).

Keep in mind that the sensor may be reading correctly but other items are preventing the EGR from flowing as it should including items such as:

Clogged EGR ports
Bad EGR Valve
Vacuum Regulator failure

I agree that the DPFE is a common failed item but try opening the EGR using a vacuum gauge at idle and see if the vehicle stalls. this will prove the operation of the EGR valve and the ports.

The purpose of the EGR valve or EGR system is to introduce exhaust gases into the intake stream. this reduces the temperature of combustion and lowers the production of NOx. It only opens at higher RPMS.

Well, windstarprob posted the same question on three other topics. Whoever is looking at this van should be able to scan the codes and determine whether or not if it's the EGR or the O2 sensor.

Keep in mind that the sensor may be reading correctly but other items are preventing the EGR from flowing as it should including items such as:

Clogged EGR ports
Bad EGR Valve
Vacuum Regulator failure

I agree that the DPFE is a common failed item but try opening the EGR using a vacuum gauge at idle and see if the vehicle stalls. this will prove the operation of the EGR valve and the ports.

The purpose of the EGR valve or EGR system is to introduce exhaust gases into the intake stream. this reduces the temperature of combustion and lowers the production of NOx. It only opens at higher RPMS.



My wife drives an automatic 2001 Windstar Sport with 85,000 km. We've encountered the dreaded P0401 code and from my research here and elsewhere it appears I need to check the EGR with a vacuum test, inspect EGR valve and conntecting hoses, and a possible voltage test of the DPFE to troubleshoot. Before I do so (as I am a novice) and given what DRW1000 said about the high RPM, does the following info change or support the DPFE/EGR path...

- No real change in performance is noticed.
- After clearing the code my wife was able to take the highway 20 minutes to work with no problem. On returning home the code reappeared.
- the vehicle has no issues up hill or with acceleration.
- Unable to reach 4000 RPM in neutral as the vehicle appears to be "choking'/sputtering.
- only ever had fully synthetic oil in it (mostly Mobil 5W30)
- regular maintenance on schedule for first 7 years (under extended warranty) with our local Ford dealership
- last 2 oil changes not done on schedule (the first a few weeks late, the most recent 2 months late - Just done a few days ago)
- regular unleaded fuel has been used the last several years (prior to that premium unleaded was used most of the time)

Thanks for any further info!
RangerG


1984 Topaz GL - 10 years of solid service
1994 Escort - still on the road, like new (only 75k)
1994 Ranger XLT - passed on to my older brother at 100k
1999 Escort ZX2 - totaled/write off
2001 Windstar Sport - Good service, low km as above
2006 F150 - US purchase when Can$ above US$ - was supposed to be a Mazda 3!

Most common causes of P0401 are defective DPFE, clogged EGR ports in the lower intake manifold, or maybe a vaccume line off or broken between the EGR valve and the EGR vaccum modulator.
Also check the hoses that go from the EGR pipe to the DPFE.

The EGR valve RARELY fails.

The signal from the DPFE tells the PCM how much flow there is through the EGR pipe.
The PCM uses this signal to determine what signal to send to the EGR vaccum solenoid......to control how much to open/close the EGR valve.
The EGR valve will be closed at idle in the driveway.....the PCM calls for the EGR flow only during certain driving conditions.

For the P0401, a defective DPFE could cause lack of signal when flow is present.
Clogged EGR ports in the lower intake manifold could cause lack of the ability to have the desired flow as called for by the PCM, even with the EGR valve fully open.

As for the 4000rpm, there may be a rpm limiter in Neutral or Park that limits the maximum RPM......I do NOT recommend reving the motor in the driveway like that anyhow.

Ok so I am having the same code, same problem. I have already done the TSB and just this past weekend cleaned the EGR ports again as they were once again in bad shape. I changed the DPFE about six months ago, and have had no change in anything. The Van gets about 10 miles to the gallon, should I go ahead and buy the egr valve to see if that is the real culprit. Dont know much about cars or working on them , but have taken off the vaccume line on the EGR valve and it has suction to it. I would love to get rid of this van but can not afford anything else, but I really cant afford the gas mileage either. Any help or suggestions would be great

The EGR valve should not be open at idle. Are you sure there is vacuum on the control hose? Measure with a mity-vac pump/gauge to be sure. If there is, you have some control issues ... bad/new DPFE sensor ... switched sample hoses ... ???

Are the sample hoses the 2 coming out of the DPFE, and if so would they not cause the van to run bad or rough? does the left hose go to the top or the bottom ofthe tube?

Are the sample hoses the 2 coming out of the DPFE, and if so would they not cause the van to run bad or rough? does the left hose go to the top or the bottom ofthe tube?

I am going on memory here as I changed my DPFE about a year ago. If I remember correctly, my 3.8L 2000 SE rig had different I.D.'s on the two vacuum hoses and thus the stubs of the sensor. They were only slightly different, like 1/4" and 3/16" so to make the installation "keyed". I guess you could have gotten them backwards but one would be fairly loose and the other would have been real tough to put on.

Yeah I checked them and they seem to be in the right spots, thanks for the input. T he guy at Advanced Auto told me to take the EGR off and clean it out and that would be fine, anybody ever done that, or would anybody do that.

FYI - if you go to Wikipedia and look up Exhaust Gas Recirculation, it will explain the entire process of what the EGR system is for and how they typically work...good info to understand when trying to troubleshoot.

To test the EGR valve is quite simple. I pulled the windsheild wipers and cowel off and then pull the vacuum line off to the HVAC system (passenger side of engine - red 1/8" hose on a 2001) and then push it together, while idling, with the green 1/8" hose that is on the back side of the engine which comes from the EGR valve. If the engine stalls, bingo the valve works. If not, the valve is stuck. What you are doing is manually forcing the valve to open by pulling, with vacuum, on the diaphram of the valve. Once you open the valve, you flood the combustion chamber with exhaust gas and the fire goes out because there is not enough oxygen to sustain combustion.

To test the DPFE sensor, you need a volt meter and the wiring diagram for your model. Test the voltage output from the sensor output (positive lead on the sensor output and negative on the battery negative). Do this with the van idling AND have someone push together the two above mentioned vacuum lines so that you FORCE the EGR valve to open. If the voltage changes before the van stalls, the sensor is OK; i.e. it measured a change and was sending the reading back to the PCM. If the voltage sticks and doesn't change when vacuum is applied to the EGR AND the van stalls, then the sensor is FUBAR so go buy another one. Now this is not gossible, but from my experience and a few other people I know, do NOT buy the aftermarket sensor. I bought it because it was half the price. It lasted exactly 6 months; same as my friends. Then I bought the Ford sensor. This has been installed for only about a month, so you never know, it may fail again too, but at least then I know for sure if buying the after market one was a problem or not! Original DPFE sensor in the van lasted about 130,000 km or 8 years.

Thanks for this thread. I've got a 2001 Ford Escape that has had the check engine light on for awhile. I had it checked at autozone and it was showing the P0401 - Insufficient EGR flow code and I needed to go through DEQ soon.

I tried replacing the EGR valve, resetting the codes and driving for awhile, but the code popped up again. So, I returned the valve and purchased a new DPFE from my local dealership. ($64.99 in stock)

It took a few minutes to switch out, reset the codes again and have driven about 25 miles with no check engien light. I took through DEQ yesterday and it passed. Good deal! Thank you!

My 2000 had a vacume leak on the black knob looking thing right on the front of the plenum. I don't know the name of the part but it is dead center right on top and had a little rubber boot on it. That was the problem. The tube the little boot plugged into was cracked and all I did was wrap it with some electical tape and plugged it back on. Good Luck

Rob

02 ford windstar has the p0401 code...has anyone had it run rough as well?..vehicle stumbles and back fires but only has the p0401 code...any ideas?

P0401 is EGR flow lower than expected.
This is usually caused by a defective DPFE (which is what measures the flow through the EGR syste) and clogged EGR ports in the lower intake manifold
Either one could cause this code.

Clogged ports......instead of the EGR flow going to 6 cylinders.....all of it is going to only 1 or 2 ports....causing them to be starved of oxygen anytime EGR flow is called for.

Defective DPFE.....reporting less flow than what you really have.....so the PCM is opening the EGR valve more to try to get the flow signal that it wants from the DPFE.......causing way too much EGR flow......resulting in not enough oxygen to the cylinders.

I had this problem and I swapped my DPFE with my 1995. No change. Swapped it with my brother's 2003 DPFE, no change. Started looking around and the hoses go from the sensor down to a tube that brings exhaust gas to the EGR valve. The nipple that it connected to had broken free and thus was screwing up the reading.

Sidenote....the rubber hose was very nasty on the inside, so I replaced. Problem has not come back.

Hope that helps.

Mark

so tell me andrew exactly how will the voltage change if you test the constant voltage going into the sensor and not the signal wire??????????? i also believe you posted that 4.6 voltage that never changed, once agaian on the hot wire not the signal the sends info. had you been on the signal you will have low voltage on start up and increase to 4 to 7 volts when hot sending a signal to the pcm and controlling egr appropriately. thought this should be resolved before anyone tried this crazy technique of yours

so tell me andrew exactly how will the voltage change if you test the constant voltage going into the sensor and not the signal wire??????????? i also believe you posted that 4.6 voltage that never changed, once agaian on the hot wire not the signal the sends info. had you been on the signal you will have low voltage on start up and increase to 4 to 7 volts when hot sending a signal to the pcm and controlling egr appropriately. thought this should be resolved before anyone tried this crazy technique of yours


Go ahead and tell the world all that you know. I know that I tested this about two years ago and found it to work because when i tested the new unit, the voltage changes. Perhaps you just don't understand. Either way, I only tried to help by offerring my thoughts and if you think you are correct, fine by me, but perhaps you just don't understand and should think before you post.

well said! think before you post. if you pull the vacuum lines off the intake with it running you will create a lean mixture increasing your idle and not find any problems except a leak.nothing in your post seemed to be relevant to testing the feedback switch or any worthy tech info all you know is you did some stupid stuff not knowing what you were doing. and in the end you listened to someone with knowledge and resolved your issue.:flipa: