1998 Expedition Diagnostic code P0401 Insufficient EGR Flow
 

I pulled a P0401 code for my 1998 Expedition V8 4.6L 4WD (111,000 Miles). I have read a couple of different posts about the EGR valve and the DSPE Sensor. As a relative newbie to the Expedition where are these located on the engine and which should I try to change first (if at all).

Looking for some advice to save some $$.

Thanks,

jarrettcox
 

Hi

I have the same vehicle and the same problem. Have you fixed the problem yet. What all have you had to change on it. Please Help if you have any ideas or have learned any thing new.

I have absolutely no idea where the EGR valve is on an expedition, but Ill venture a guess since this thread lacks other replies and say that I think something in the EGR system may be carboned up and need a cleaning or replacing, which would be a pretty simple problem to fix, but a gremlin to locate.

Again, I know nothing about expys, my EFI experience comes from a Mustang....

Any of you Expy guys have any thoughts?

Thanks I can really use the help.

Suggest you goto Autozone and purchase a $15 Manual, it has hundreds of pictures, details of install, removal, testing and function of alot of parts. It should suffice for a "home mechanic".

The DPFE (metal if OEM, Black plastic if it has been replaced, is located on the drivers side of the engine on my 99 4.6L EXP, is 3 in long, 2 in tall and .5 in thick), has 2 fuel line type hoses on one end and a cable harness.

The EGR Solenoid is a black 2 in tall cylinder, 1.5 in diameter, with 2 vacuum lines and a cable harness.

The EGR Valve is a 3 in metal cylinder, 1 in tall, with 1 in diameter connections with 4 bolts, and have a vac connection on the top.

The manual suggests ways to test each component, in logical order...

I had a DPFE problem on my 99 Taurus, and changed out parts with my Exp, to confirm my suspicion of a faulty DPFE.... NOTE the DPFE on a 99 Taurus is very hard to get to as compared to the EXPY....

I had the same problem with mine. The problem turned out to be the tube was clogged for the EGR valve. Tried to clean it out but that was a waste of time. So after I installed a new tube, the problem went away after clearing the code.

Has any one checked their air filters lately? Plugged up AF could pop a low airflow code in most vehicles as well. I'm not trying to detract from the already noted EGR problem, just trying to throw in another idea. I find that most shops go right past the simple and cheap, and start tearing into the most expensive possible causes just to find themselves right back at the $10-$20 fix.

I had the same problem with my 01 expy. it was the DPFE sensor.

freak4ford you mentioned changing the tube on the egr valve, ( I am a female LOL) so which tube is it you changed or is there only one tube.

Always gotta be good to MOM... The runs from the EGR valve down to the crankcase. Its metal, silver in color located on the drivers side. I have the 4.6 1998. I imagine its the same on the 5.4

same vehicle and the same problem...I have replaced the EGR valve, and DPFE sensor. Still the same code (p0401) 24 hrs later. When the engine is cold it will not idle high enough to run, I have to manually give it gas to warm up. I assume this is related but don’t know as no code other then p0401 shows up. Even if I disconnect the EGR vacuum it wont idle. The theory being that the vacuum is opening the EGR causing it to low idle...not the case. I have read about the ports being clogged, but that would be the same as the EGR being closed...again, that shouldnt cause the low idle. Only when the EGR is open will the engine idle too low...right? What else could the problem be? Im at the end of my rope.

I have a cheap Haynes book I purchased from AutoZone. It gives checks that can be done with a meter. Pin a to pin b, so much resistance, replace if under/over and so on...I would suggest spending the 15 bucks and going through the checks to try and determine what is out of limits.

At first glance, without having my manual and going out of memory from over two months ago, it sounds like your EGR valve is actually being commanded open for some reason when the engine is cold. Does it run normally when warm? Is your engine a high mileage oil burner (coking up valve assembley)? THere is also a chance the sensors are telling the ECU the valve is open when it is really not and the ecu is compensating, causing the engine to run poorly. Just some thoughts...Good Luck and post the fix when you solve it.

Yea, I tried going through the book and testing all the points. They all seem to be within range. It does run fine after warming up, and yes, high miles (92,000). The EGR valve is new, but even the old one was pretty clean.

Just went thru this. For me I pulled the throttle body off to find the 2 chambers for the EGR where totally clogged Pretty simple stuff. Make sure you have a new throttle body gasket and EGR gasket beofre removing. Issue resolved.

Thanks, I will try that this weekend...and post results.