Hey guys
i tried posting this in 4.6, 5.4 Modular V8 forum about a week ago and nobody replied so i thought i would try here.

i have been reading alot about the 4.6 with a p0401 code but cant seem to find much on the 5.4. I have a 99 5.4 with 130,000 on it and it just recently threw the p0401 code so i cleaned the ports on the throttle body as well as the ports from the exhaust manifold, cleared the code and it keeps coming back. A lot of people say that the problem is clogged ports and that the EGR vavle rarely ever goes bad but is it possible that the DPFE is bad, if so is there any way to check it before i buy a new one it's only about $50 but i would rather not spend it if i didnt' have to. Another thing while i was taking the TB off i dropped a bolt down underneath the intake manifold does anybody have any words of wisdom on how to retreive the lost bolt. Is the p0401 code as common on the 5.4 asd it is on the 4.6?

Thanks in advance for all the help
Smits03

 

9 out of 10 times, if the ports are clean, it is the DPFE sensor.
A lond flexible magnet may retrieve the bolt.

 

As for the second part of your question, yes it is just as common with the 5.4 as the 4.6 and also very common with the 3.8 car engines. On the 5.4, usually you don't have to clean the ports. I have never seen one stopped up. The DPFE sensor will fix it everytime. However, the 4.6's are bad about the EGR ports clogging up.

 

thanks guys for the help, i'll try a long magnet again this weekend, i tried last weekend but couldn't get a hold of it. luckly my brother used to work at the ford dealership here in town so he had a bolt in the junk drawer that is getting me by until i get the other one back. i'll keep you posted on the fix.

 

well i changed the DPFE sensor at noon, reset the light and it come back on tonight after work. so i guess tomorrow i will take the intake off again and try cleaning it out some more.

 

Before you go nuts on the TB check out some easier stuff first, like the EGR test and testing for vac to the solonoid... I have a 5.4 and it is virtually immune to the port issue. Do a search on this site and you'll find out how to test the whole system front to back.

 

ok guys i need some advice. i cleaned the TB changed the DPFE Sensor, blew out the line coming up from the exhaust manifold and i am still getting a p0401 code. i know that after my pickup has been running for over an hour and is good and warmed up to line coming up from the exhaust manifold is still cold by the egr vavle. should it still be cold or will it never warm up? to me it should warm up because the exhaust gas is hot and some of it gets recirculated through that line which would lead me to believe that it should get hot, so does that mean the the egr valve is not opening? i know that i have vaccum to the egr valve, so i'm wondering if the egr valve is bad. any advice would be helpful.

thanks,
smits03

 

smits03....I have the same problem and 98 vehicle as you. I have gotten alot of great info from the generous people on this site. But, I'm sad to say that as far as I can tell this topic is a buy and try fix. I hope we get more suggestions. After each service item, in 30 miles or so the p401 is back. On the p401 I have...
replaced egr and new gaskets
cleaned tb and plenum passages
replaced dpfe sensor thing
check and replaced pvc and piping
previously replace maf sensor
replaced air filter with k&n

Any more help out there.......anyone who's not guessing???? Thanks.

 

well, i think i finally fixed it. yesterday morning i changed my egr valve, the old one was stuck closed. i have driven over 100 miles and no ses light.

 

To check the egr valve take a vacum pump and pull a vacum on it while idling. The engine should start missing this is normal also your egr valve, dpfe, and egr solonoid will not work untill the vehicle goes threw a open loop mode- Two drive cycles with complete engine warm up over 30 MPH

 

Well, 2 drive cycles before they work. I haven't heard that before but I'm starting on my 3rd drive after clearing the codes. I'll be happy as a lark if it stays off. I'll let you know!!

 

It takes two drive cycles to complete some obdII test.

 

Well, the p401 is back after the 3rd drive and reset. Anyone with another suggestion on what's next to check or replace??

 

On our Expedition (2001, 5.4l), the reoccurring P0401 was due to a defective MAF sensor. Some have said than cleaning the MAF works, but in my case it needed to be replaced.

 

""2Fords1Jeep On our Expedition (2001, 5.4l), the reoccurring P0401 was due to a defective MAF sensor. Some have said than cleaning the MAF works, but in my case it needed to be replaced. ""


MAF , well. I haven't heard that was even related to the EGR system. It was about a year ago when I replaced mine so I will revisit that booger. I'm not accustomed to this thing of not getting problems resolved...I hate OBDII !!

The catalytic convertor on my wife's Regal GS clogged and the car would barely go. No warning/check engine light ever came on. Smart sytems.

Computers, warning lights, and internal combustion engines don't go together. Must be the same group of engineers that decided that a coastal city several feet below sea level, next to a big lake was a good idea.