Ford P0401 Code Scanned – Expedition 4.6 EGR Low Flow
July 7, 2009 9:42 pm DIY, Ford Problems, How To Auto Repair
2000 Ford Expedition P0401 doesn’t necessarily mean the EGR is bad
Summary: Ford DPFE problems discussed. Common causes for Ford EGR low flow issues and P0401 fault code triggered. Don’t replace the EGR (Exhaust Gas Recirculation) valve just yet if you have a P0401 code on a 4.6 liter engine like the one in this Expedition. The diagnostic code definition states “Low flow from E.G.R.” Low flow doesn’t mean definitively that the EGR is bad. Low EGR flow can be a problem in any Ford, Mercury, Lincoln, Mazda and many other car’s for that matter. On a lot of Ford vehicles this code will mean there is a faulty Differential or Delta Pressure Feedback (DPFE) sensor. This was such a common problem there was an extended warranty coverage on them for awhile. Not many people knew about Ford covering these on some models for an extended period of time. At the shop I worked at, an extended warranty company first alerted us to this when they declined an extended warranty claim because Ford would replace it under warranty.
What is a DPFE and what does it do?
The DPFE helps the vehicle’s computer to insure that the EGR (Exhaust Gas Recirculation) system is working properly. The sensor monitors the exhaust pressure in the exhaust, usually from a passage in the vehicle’s intake. The sensor sends a reading to the vehicle’s computer. If the expected changes in pressure are not seen by the PCM (Power Train Control Module) the CEL (Check Engine Light) will be turned on. Most of the time performance issues aren’t noticeable. Sometimes pinging upon acceleration can be detected if the DPFE is not working properly. It is usually located near the EGR, in fact some late model Ford’s have the DPFE built right into the EGR. The sensor is prone to failure mainly because of the harsh exhaust it is exposed to. Between carbon build up and corrosion, a bad DPFE is a common problem. On the 2000 Ford Expedition, the original DPFE was aluminum… it doesn’t rust! The problem is that aluminum does corrode. The replacement DPFE is made of plastic, which is an improved design but failures of these are still fairly common.
With throttle body removed and mirror in place the passages can be seen
The two dark spots are two badly restricted EGR passages
EGR Passages
The passages on the Expedition in the picture above are shown with the throttle removed. They are obviously restricted, completely blocked off with carbon build up. The passages go down, then to the right where they meet with the EGR. With the EGR removed, the passages can be cleaned out with fuel injection spray cleaner, a spare coat hanger and a thin bottle brush from the kitchen. Compressed air helps blow through the gunk and clear the passages, allowing the EGR, DPFE and PCM to work together.
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Vacuum can be applied to an EGR with a hand vacuum pump, while it’s running to see if the idle drops. Sometimes the idle can drop some but the passages may still be partially clogged.
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When replacing a DPFE sensor, if there are rubber hoses, blow through them with compressed air to clean out any loose debris.
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Replace DPFE hoses that have excessive deterioration. Regular hoses won’t work, it takes special DPFE sensor hoses to withstand the high temperatures.
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Try cleaning the EGR passages first to attempt to save money. Replace the DPFE sensor if the diagnostic code returns.
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Don’t buy a used one, this is such a common problem chances are not good to find a good one in a salvage yard.
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The diaphragm in the EGR can leak but it’s not as common as the above mentioned problems.
alan :
Date: September 16, 2014 @ 7:22 pm
Thank you. I’ll clean the ports and see if that works.
alan :
Date: September 17, 2014 @ 9:23 pm
OK I took off the throttle body and checked the egr port and it looked like someone had already cleaned it. It was clean and clear all the way through. Probably the previous owners. I have only had it for 2 years. What do you suggest next? So far I have replaced the egr valve, cleaned the 2 hoses from the dpfe and blew in them to see if they were clogged in the pipe that goes from the EGR to the exaust and it seemed clear. Thanks for your help.
dennisb - Auto Tool Sales :
Date: September 18, 2014 @ 7:50 am
Alan, the most common cause is clogged ports. That’s plural – ports. Sometimes it can be a bad DFE, but it’s important to clean both EGR ports. I’ve cleaned ports before and have had carb cleaner spray all the way down to where the EGR mounts (with the EGR removed of course). And have still had the low flow code come back after clearing the codes and driving it a while. So what I’m saying is the EGR ports have to be completely clean not just partially clean. Now the pipe is for exhaust. That’s not the EGR port the code or this article is referring to. Let us know what you or your mechanic ended up finding. Good Luck.
Bluemelodie :
Date: September 26, 2014 @ 3:20 pm
Hello! I have a 1999 Ford Expedition. Recently, when I crank it up it does one of two things. Either it revs high above 2000rpm for a moment, then back down and is fine. OR it barely starts staying below 500rpm and sometimes dying. I still have to drive it to work, so I just make sure I accelerate ever so slowly, and don’t take my foot off the accelerator too quickly. It continues to hover around 500rpm usually. After driving awhile, sometimes it straightens out. But still sounds a bit rough. I took it to Auto Zone and got these codes:
P1401, P0401, P1507, P1450
Someone said I could just run it and spray throttle body cleaner into the
EAC to clear it out and maybe fix it. I really can’t afford taking it to a mechanic. Any help to fix myself would be really appreciated.
dennisb - Auto Tool Sales :
Date: September 26, 2014 @ 3:54 pm
The IAC can cause an erratic idle, but so can a vacuum leak. You may have several issues but for the idle issue I’d be checking for vacuum leaks first. I’d also check the EGR passages although I don’t think that would cause an idling issue only the P0401 low EGR flow code. After fixing the vacuum leak, if you find one, and clearing the EGR passages, I would clear the codes to see if any codes come back. Good Luck.
Code definitions/info. P1450 DPFE (Differential Pressure Feedback) fault. This is a very common Ford problem. Replace it and clean the hoses or replace them if they are degraded. P0401 – EGR low flow, read the article above. P1507 Posible IAC (Idle Air Control) issue. P1450 – Evaporative emmission issue could be related to the other problems. Has to do with fuel vapors.
Karen :
Date: September 28, 2014 @ 11:08 am
I have a 1997 ford f150 I have done everything to it . I have changed all 4 O2 sencors and have driven it I have used that guaranteed to pass and driven it 285 miles. And still it says that all 4 O2 sencors are still popping so I cleaned the mass air flow . And its still not clearing what do I do. Iam to my wits end . Please help me.
dennisb - Auto Tool Sales :
Date: September 29, 2014 @ 7:22 am
Karen, I’ve never heard of guaranteed to pass or of O2 sensors popping. I would check the EGR passages if the P0401 code is set. Good Luck.
Josh :
Date: October 3, 2014 @ 10:17 pm
I have a 2000 F150 XLT and I’m getting a Po401 code which I’ll assume is egr low flow. I just reworked the heads, replaced timing chains and all gaskets. The DPFE sensor is new and EGR ports are clear. Any ideas? Could it be the EGR solenoid or just the EGR itself? Acceleration has a slight flutter when accelerating up to speed.
dennisb - Auto Tool Sales :
Date: October 4, 2014 @ 11:44 am
Josh, I would double check the ports as outlined in the article. Good Luck.
Josh :
Date: October 5, 2014 @ 12:25 am
They are super clear. EGR perhaps? That’s my educated guess. Any thoughts? Thanks!
dennisb - Auto Tool Sales :
Date: October 5, 2014 @ 8:32 am
Josh, in my experience low flow means low flow from a resticted passage not a faulty EGR. Good Luck.
Juan Quintana :
Date: January 6, 2015 @ 4:15 pm
I replaced a lot of parts that make the p0401code show up on my 1998 f150 4.6 and now when i start my truck in the cold morning it doesn’t want to start. Then I’ll come back about a half hour later and it starts right up. Can anyone tell what this could possibly be?
dennisb - Auto Tool Sales :
Date: January 6, 2015 @ 5:47 pm
Juan, I would say the problem could be unrelated to the EGR restricted flow issue. I’d check fuel pressure and see if there are any pending codes. Good Luck.
Carl :
Date: January 14, 2015 @ 6:56 pm
My ’03 Lincoln Navigator started doing a sort of jerking/stuttering thing whenever I accelerate between 45-60mph. It threw a CEL so I took it to get checked out and codes 0401 and code 1450 came up. Could these codes be related and causing the jerking that I’m getting while accelerating in that speed range?
dennisb - Auto Tool Sales :
Date: January 15, 2015 @ 11:05 am
The codes you have are related to the EGR and EVAP systems. I would fix those and see. However I don’t think those would cause the jerking/stuttering. Fords have a common problem with torque converters causing this. I would have a transmission flush performed (not just a regular service). This changes ALL of the fluid in the transmission and converter as opposed to the regular trans service that only changes about a third of the fluid (what’s in the pan). Good Luck
Carl :
Date: January 15, 2015 @ 8:27 pm
Well I took it to an auto repair shop and they said that the EGR valve could cause a build up in back pressure if it failed which in turn could result in a cylinder misfiring which could cause the jerking/stuttering in that speed range. Does that sound like a reasonable hypothesis to you?
dennisb - Auto Tool Sales :
Date: January 16, 2015 @ 7:55 am
Carl, it is possible. I would make repairs to get rid of the codes and recheck. Good Luck.
Chris :
Date: January 24, 2015 @ 3:12 pm
I have a 2004 ford f150 and I was replacing the spark plugs and when I broke a green line coming off what i believe to be the egr. After which a p0401 code came up. I shrink wrapped the broken ends together and cleared the code. Would the broken line cause this code to come up? And how do i remove the line to replace it? Thanks
dennisb - Auto Tool Sales :
Date: January 26, 2015 @ 7:53 am
Chris, a broken hose for the EGR could definitely cause the code. I would follow the line from beginning to end and removing them should be self explanatory. Good Luck.
Reiko :
Date: March 16, 2015 @ 11:46 pm
I have 1998 Ford expedition RIGHT AFTER I pumped gas I put in drive there was no gas flow just died out then started it and kept dying out. Changed fuel filter there was bunch of black stuff floating on top of fuel that came out of filter sound like it wanted to start but still no gas flow to stay on.what could be the problem?
dennisb - Auto Tool Sales :
Date: March 17, 2015 @ 7:28 am
I would check fuel pressure, the pump may have failed. May have just been a coincidence because the truck should have ran on the fuel that was already in the lines without getting to the newly pumped fuel for at least a minute. Good Luck.
Bryan Vincent :
Date: July 16, 2015 @ 7:22 pm
I have a 97 ford f150 with the 4.6 in it and it shows p0304 code for cylinder 4 misfire but I have changed coils, wires, and plugs before I had my catalytic converters replaces from were a previous misfire caused them to catch fire and have a meltdown. I had to replace the transmission in it but the truck sat up for 6 months before I started driving it again. The cel flashes but I don’t know what could be the cause but just the gas since I had a complete tune up done. Would it just be the gas?
dennisb - Auto Tool Sales :
Date: July 17, 2015 @ 10:14 am
Bryan, bad gas would affect all cylinders not just #4. The most common causes of a misfire on a particular cylinder are spark plug, coil, injector, compression etc. Good Luck
mike :
Date: October 20, 2015 @ 6:08 pm
I have a 2001 Ford Expedition that will start and run OK for about 10 minutes and than stalls. After letting it sit for a few minutes it starts but repeats the same problem. What could be the problem. Thanks.
dennisb - Auto Tool Sales :
Date: October 20, 2015 @ 6:36 pm
If no codes I’d check fuel pressure. Good Luck.
Hector :
Date: November 21, 2015 @ 5:19 pm
I have a 2001 f150 4.6
137000 miles the problem im having is
At start after warm up if i turn it off i have to crank three times to start ,it runs fine plenty of power i just changed the fuel filter thinking it maybe clogged it does it 90% of the times could my pump be going bad ?
Thanks in advance.
dennisb - Auto Tool Sales :
Date: November 22, 2015 @ 10:38 am
Hector, the fuel pump could be is losing it’s “prime” allowing gas to drain back down the line. But this is usually after it has time to cool. It would then take some time for the pressure to pump back up. You can check with a fuel gauge. There should be some pressure maintained and it should not leak down when the engine is off. I’d also clean the throttle plates, because carbon build-up can take up some space in the throttle throwing off the computer’s air intake calculations used to add the proper amount of fuel mix. This could cause a delay in starting also. Also, carbon build-up in the engine can hold some fuel aggravating the issue. Good Luck.
Howard :
Date: February 1, 2016 @ 5:16 pm
I have a 1999 Mercury Sable 3.0 DOHC LS got P0401 code since October 2015. First started from clearing EGR valve and pipes, follow by changing new DPFE hoses, DPFE sensor, EGR solenoid then a new EGR valve. but the P0401 error code keeps coming back every time after I changed the parts. The P0401 error code only come back right after I do heavy acceleration. Also, I am in New York, we have a warm winter this year, I have noticed that the P0401 code only come back when the temperature is above 50 degrees Fahrenheit. If the temperatures is below 50 degrees Fahrenheit the P0401 error code won’t come back even I do the heavy acceleration. Does anyone know why?
Thanks.
Shirley :
Date: February 27, 2016 @ 4:54 pm
I drive a 1998 Lincoln Navigator. Because of PO401 & PO455 codes and the check engine light continuously staying on, my brother & I replaced the gas cap and the EGR valve. The PO455 code was eliminated; however, the check engine light is still on and PO401 code displays (according to Advance Auto). They told me to drive my car for several “cycles” and the light should go off. I drove the car today for about 90 miles, stopping occasionally for 15-20 minutes, then starting back up and driving again. The light is still on. Will it go off after a few more “driving cycles”? I have to have the car pass inspection by Tuesday. Help!
dennisb - Auto Tool Sales :
Date: February 29, 2016 @ 12:12 pm
I would check for blocked EGR passages. Driving more cyles without fixing the problem will do no good. Good Luck.
Xavier :
Date: April 22, 2016 @ 6:36 pm
P0750 p0112. P1747 codes
dennisb - Auto Tool Sales :
Date: April 25, 2016 @ 7:47 am
Sorry looks like different codes than what this article covers. Good Luck.
Bill :
Date: April 26, 2016 @ 11:24 am
Temp related P0401? My 2002 EX 4.6 brings up the code only when the outside temp is above 40F, all winter no 0401 code, now this spring the code is back. I have replaced everything. I flat out give up.
dennisb - Auto Tool Sales :
Date: April 26, 2016 @ 11:31 am
I’d clean EGR ports like article covers. Good Luck.
Bill :
Date: April 26, 2016 @ 11:43 am
Throttle body was removed, and cleaned. Could the catalytic converter be causing the code to appear.
dennisb - Auto Tool Sales :
Date: April 26, 2016 @ 12:19 pm
No, the catalytic converter clogged would cause an efficiency code and bogging (lacking the ability to accelerate). Clogged egr ports are most likely the cause of the the low egr flow code. Taking the throttle body off and just spraying some cleaner is not good enough. The ports can be completely or just partially clogged and the code will be set. If you feel like you have cleaned the ports thoroughly and the PDFE has been replaced. I’d say it’s time to take it to a shop and let a professional take a look at it. Good Luck.
joseph v. :
Date: May 28, 2016 @ 11:58 pm
Hi I have a 99 expedition 4×4 eddie bauer that runs good but just recently when I take off from a stop between 25 35 mph it hesitates and also when im trying to keep at the above said speed it does it so I have to give it some gas to stop but the tranny and motor are strong it shifts perfect I changed crankshaft position sensor camshaft position sensor o2 sensors but it still does it!! Any idea what else it could be?
dennisb - Auto Tool Sales :
Date: May 29, 2016 @ 9:41 am
Sometimes it’s hard to tell if it’s a tune up issue or a transmission issue. Misfires on Ford’s sometimes will take awhile before a code is set. I’d check Mode 6 see my mode 06 misfire article. I know you said that it shifts perfectly but, sometimes a harsh shift can cause a similar sensation. If there is a slight spark knock during acceleration it could be a bad DPFE. Good Luck.
Jake :
Date: September 19, 2016 @ 10:01 pm
I have a 2003 expedition 4.6L 2 wheel drive.
My problem started yesterday when me and the family drove across town about 30 miles, we shut it off got out for about 45 mins or so. When we got in to leave, I turn the key to crank there’s no hesitation but a quick knock and crank then there’s no noticeable knock at that point, so I tap the accelerator to rev just a little and there’s alittle tap and as the rpms come down then back at idle no noticeable knock. Anyways we head home the only time I can tell it does it when I start to slow down going back to just an idle at a red light or stop sign and since its warmed up there is a very faint slight tap/knock when idle at a light.
So I go to the part store and get the engine light reading and it’s the p0401 code! So I go through checking the egr system and everything seems fine I replaced the dpfe about 4 months ago after breaking one of the little tubes by accident trying to replace the valve cover gasket. So I pulled the throttle body and all off today and the egr holes were severely clogged to where I had to use a small drill bit to slowly unclog it and a bunch of break clean! So if you could please help I would appreciate it a lot!!!!
The only other thing I’ve had an issue with it lately is the passenger side valve cover breather tube the 90 elbow had a hole in it.
dennisb - Auto Tool Sales :
Date: September 20, 2016 @ 7:10 am
Sometimes a slight spark knock could be DPFE related but if it’s a more severe knock there could be be engine wear or the engine could be low on oil. I’m sure you probably checked the oil level and condition. So a visit to a shop for an opinion from a mechanic that has the benefit of hearing the noise first hand might be in order. Good Luck.
Jake :
Date: September 20, 2016 @ 10:34 am
yeah I checked the oil it was fine.
Thanks I appreciate it.