The thread is a bit old.
If your asking about a P0401 code and replacing a converter for it; no.
There is no relationship of a 401 code to a converter fault.
.
A 401 code is a low flow EGR test failure.
The cause is a blockage for a low flow.
The causes are a blocked port behind the EGR.
A faulty DPFE sensor.
Vacuum delivery through the EVR or the hoses involved.
Seldom it the fault the EGR.
Good luck.

 

Hi, my '98 4.2 had the 401 code for the last several months, I had it in for diagnosis at the dealer's several times and the advised replacement parts failed to fix it. I replaced the DPFE and DVR valves, cleaned the TB, pulled the plenum (twice) and cleaned the EGR ports and the valve..still the code. And yes, the EGR valve tested out fine. Finally, on about the 5th trip to the dealer, the tech said he noticed one of the two plastic lines feeding into the DVR valve (pass. side of engine) had a crack at end.. he snipped off bad end and reinserted...fixed!! Finally!...no more light! These are the colored lines, green and red I believe. Hope this helps someone.

 

my 97 4.6 f150 got the P0401 code (insufficient egr flow) i changed the DFPE sensor egr valve itself and cleaned the throttle body and a vacumn hose and the check engine light keeps coming back on...any idea on what it could be and how i could fix it?



Thanks, Mike

 

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Clean the ports 'behind' the EGR. Likely plugged with carbon.
If you had tested for flow before doing all the other things it would have shown up.
Within the very long thread, is all the info on it.
Good luck.

 

I have found two vacuum lines dry rotted at the base of vacuum regulator . One feeds vacuum to EGR (green vac line) My truck had intermittent surging MIL light on and off Code p0401 . I also had p0306 i changed the coil on cylinder #6 (second time i have done this) I don't think this is related to the 401 code but i did have an intermittent lean code at one time . My truck has very high mileage and i have found other rubber hoses and vacuum lines soft attacked by age and oil. Vacuum very important !!! and an inexpensive repair. DPFE sensor was bad filled with water .

 

99 F150 5.4L 184.000 miles My P0401 code was the DPFE sensor. This is the Second one I have replaced the first was aluminum body and heavily corroded and wet. The other was plastic body and ya can shake the water out of it. This took care of the surging and the MIL lamp. I also had many dry rotted vacuum lines that supply vacuum to the vacuum regulator and the EGR Valve. My 150 has very high miles and the EGR ports were very clean just varnished. I put a Vacuum Gauge on the lead going to the EGR and watched the Vacuum . Off at Idle Off under Acceleration and about 5 ins when going down the road. The Vacuum snaps to 0ins when TB is closed. With the EGR Vacuum plugged the surging went away . A clue that the valve is working and the DPFE Sensor is not ! I also had a bad coil on #6 wet,oil ,water and dirty .That cleared the P0306 . The coil on #7 was wet and had sand in the plug hole holding water and giving me a misfire with out setting a code. I also heard an arching pop coming from #7 after a all night rain. I replace 6 coils so far and all the spark plugs cleaning all the holes and coils.I had about 80,000 on a set of Autolight Platinum . #3 had a loose spark plug giving me a tick or what i thought was an exhaust leak under acceleration . I would look at Vacuum lines first and hoses . Check DPFE for water . I have never had an EGR Valve go bad but have changed it just to check the port . I gave it a good TB Service Air and Fuel Filter and PCV . Running good again. Im watching how things are getting wet ! My hood does not fit well ect . eddiemoyer@hotmail.com

 

dreaded 401 code...have put vcuum to egr valve and the engine bogged down...checked voltage to dpfe sensor, got 5.0 volts on the reference and .14 volts on the signal...what else can i check..

 

You cannot test the DPFE sensor reliably with just a voltage test.
It has to respond to pressure changes. Voltage checks don't tell anything about it's ability to do that.
Replace with a Ford part only.

 

2001 F-150 4.2 v6 2wd AT 218684K miles
I have been reading this thread for the past couple of days and thought I would share my experience.
Truck was hardly running valve clack like it was going to blow! No codes or "cel". Mechanic tells me it the EGR. He replaces it for $220 and there is no improvement. Now I am mad enough to kick a brick wall.
I found this thread and started to learn about the problem. Last night I replaced the EGR Vacuum Solenoid (took 20 minutes while drinking beers). Problem improved 90%!!!!!!!
Still idling rough so, tomorrow I am going to try to change the DPFE sensor. About five years ago I had the upper and lower intakes removed, cleaned, and re-gasket-ed with the new and improved gaskets to prevent the blow-by.
I am beginning to develop the opinion that the whole EGR vacuum system needs to be replaced all at once.

 

hello deadmike,
Whata name!
What is going on?
You have valve noise or just rough running?
If there is an EGR system issue, it should set a code.
It seems to much guessing cost you money in lue of knowing what the issue is and addressing it.
Maybe we can steer you a bit better.
Before you buy a DPFE, know that it won't cause rough running by it'self.
It's only a 'dumb' reporting sensor and does not directly control anything.
Good luck.

 

I have slight valve noise now. It got tons better after I changed the EGR vacuum solenoid. It also is running rough at idle. As I mentioned in my last post, I changed the EGR and EGR vacuum solenoid yesterday. A few years ago I removed the upper and lower intake and cleaned them and put the improved aftermarket gaskets.
Trying to sell this truck ASAP so I can keep the lights on through Xmas! My current daily driver is a 2006 F-150 5.4 V8 4WD and I love it!

2001 F-150 4.2 V6 AT 2WD 218600K miles

 

i have a 2001 f150 over 200 thousand miles it runs good but i have ben getting a p0401 p0171 and p0174 codes. I tested the egr and replaced all the valves in the egr system i dont no what to do. have any ideas.

 

dave, you should start your own thread.
Trying to offer answers to more than one poster often generates confusion.
Open a new thread and give 'all' the info on what you got and what your have done..
Your codes indicate two different problems.
Just replacing parts is a guessing game that cost you for parts you may not need as you have found out..
Good luck.

 

I replaced the EGR valve, DPFE sensor and the EGR sensor and checked all lines and had no leaks and error code continued to come up after about 10 miles. I watched a video on YouTube that explained cleaning the ports on the throttle body. I removed the throttle body and sure enough the 2 ports from the EGR valve were completely plugged. I had to chisel out the gunk and cleaned everything with throttle body cleaner. It has been a week since this was done and no check engine light yet and I can tell a difference in performance: smoother shifting, smoother idle. Hopefully the fuel mileage will pick up as well.