Been throwing off P0401 for couple of weeks now. Came on, went off, came on, went off, now on and staying. Had checked at Advanced Auto and said no other codes. Gentleman at Advanced suggested removing and cleaning EGR valve. Pulled out the Haynes and doesn't look too complicated. Always like checking with you xperts before go diving in what might end up being very shallow pool. More background: had to have DPFE replaced and had new plugs and wires while at it. Two days after replacing DPFE starting getting EGR 401 code. MPG also slipping a bit but not bad....13.5 in town.

Any suggestions other than cleaning EGR? Any advise on removing and cleaning?

Many thanks

99 w 4.6 and 116k miles

 

Code PO406 has to do with the EGR popet valve - You don't have that code , so it's not the EGR valve.

Common problem , First of all it's your DPFE that's throwing your code PO401 , That has always been a DPFE malfunction.

Ford has updated the DPFE's recently and you can only aquire the updated ones at the dealerships. Third party venders carry the old type that can fail in short period of time.

I suggest getting one from the dealership , or cleaning your old one by drilling out the rivets , cleaning the inside and replacing rivets with machine bolts and nuts from the hardware..



Heres the link you will want to check out -

http://www.fordscorpio.co.uk/egrmonitor.htm

 

Brew thanks for the info but I'm little confused. You said it is the DPFE but I just had dealer put in DPFE May 31. According to their "datalogger" they monitored PIDS and Recorded...whatever that means....when took to dealer was also getting same code but also very sluggish acceleration, and some hesistation particularly in mid gears. Replaced DPFE and runs and idles smooth.

Think your telling me still DPFE problem????

 

Yes sir - if your OBD 2 Scanner is comming back with the PO401 - It's the DPFE - I'm sure - 406 is the EGR valve itself .

I would make sure you have the updated sensor, sounds like you don't.

If it is indeed the EGR poppet valve sticking , then report back to this forum please. I seriously doubt that to be the problem..

Thanx..

BTW - The DPFE does not effect idle or a rough running cenerials..It will effect emissions and mileage..

 

It's not uncommon for code P0401 to return after replacing the DPFE. When you replace a DPFE, it's very easy to install the input & output hoses in the wrong place. One hose is larger than the other, but it's no problem putting them on the wrong nipple on the DPFE. Big hose to big nipple; small hose to small nipple.

To make matters worse, the position of the large & small nipples may be in the opposite positions on the new sensor. The big nipple may be on the left on the old metal DPFE, but it may be on the right on the new plastic DPFE (or vice versa). Often, you'll see one hose stretched pretty far to reach the left nipple on the replacement sensor.

 

+ 1 -Very true and that slipped my mind ..

 

I got the same code on my 02. I took off the throttle body and the two small inlets where the exhaust gas comes in at from the egr were completed clogged with carbon deposits. It was nasty. I cleaned them out with some degreaser and actually had to dig some out with a small screwdriver, but once I was done, no more check enging light. Might wanna try that out just in case.

 

Thanks for this info..best I've seen on the internet...This appears to be applicable to my 96 F-150 4.9L 217,000 ..I am getting P0401, P0171, and P0174..I plan to purchase a new DPFE sensor as I removed one of the hoses and noticed alot of white debris within it...I believe the 171 and the 174 codes are caused by an old PCV grommet that allows some of the gases to ventilate directly to the atmosphere. I've read alot about the clogged EGR ports on the newer model Ford truck and wanted to know if that is an inherent failure on the 4.9l also before I go and rip things apart...Does it sound like I am on the right track here?

 

Has the EGR passage through the intake elbow been cleaned out? That will also set a PO401 and is pretty common on the 4.6.

 

Did you mean to say 4.6? Not sure if the elbow you are referring to is on the 4.9 that I have. I haven't cleaned a thing...Just additive in the gasoline...Oh...I should mention that I changed the EGR valve and all lines have been smoke checked and checked good..Also new air filter and PCV valve.

 

Sorry, I wasn't replying to you. I was replying to Rail's original post.

 

These threads always seem to turn into jokes after awhile.
Why not find out what a 401 test is all about then go about the fix with a base of knowkedge instead of throwing parts around and guessing.
What is a 401? Test flow failure when the EGR is opened a specific amount by the PCM program.. This test checks the EGR, the EVR, the main pipe for integraty, the DPFE it'self, it's hoses and hookup to the PCM.
How is it measured? Using the DPFE to measure pressure drop accross a restriction in the pipe between the exhaust manifold and the EGR.
What places could cause the low flow indication? Blocked pipe restriction, EVR not opening the EGR the required amount, EGR to intake port plugged, EGR it'self, vacuum hoses to thhe EVR/EGR and finally the DPFE, it's hoses or plug/wiring.
EGR tube cracked or rusted thru.

Leave the 4.9 engine out of this because it's a straight 6 with different hardware but the operation is the same.

Testing: Use a vacuum source to test the EGR before removing it. It or the port may not be the cause.
Carefull observation of the pressures out of the DPFE hoses with the engine running can prove the restriction is open or blocked.
Do the testing and use some logic applied as to how the system works.
Clearing the code means you will wait 2 drive cycles to see if the fault is cleared because two attempts to test the function is done before a code and lamp is set.
Not part of this per sey, but clearing codes sets a P1000 until the whole system goes thru all PID tests, to sucess. This sometime means you will not pass inspection until the 1000 code clears and enough drive cycle time has been done..
Makes life a lot easier when you do things from some base of understanding..
These systems are complex and can't be treated so simply.

 

Sensor, pcv valve and grommet fixed my issue...guess I should have started my own thread...hard to find forums on the 4.9L straight six...