OK- I have read several fixes for P0401. I am still getting this code after performing the following:
1.) New EGR Valve
2.) New DPFE with new hoses
3.) New Idle Air Control Valve
4.) Cleaned carbon buildup in Throttle Body Housing-EGR Ports
5.) Cleaned carbon buildup in Throttle Body
6.) Replaced 1/4 inch PCV t connection hoses that were rotted to EVR Solenoid
7.) Disconnected battery ground for ten minutes.


I have not performed any electrical or vacuum tests. Replaced parts instead.


The parts were not motorcraft parts OEM.


Someone has to have an answer to this P0401 continuous code.

 

None of those will help a P0301 code since the code is telling you there is a misfire only on cylinder #1(front one passenger side). Look for a bad fuel injector, COP, or spark plug. You can swap those 3 components one at a time with other cylinders to see if the misfire moves to another cylinder.

 

Misquoted OBDII CODE should be P0401.


Thanks

 

Okay, what about the EGR tube that runs down to the exhaust manifold, is it clogged or broken?

 

I may have uncovered the problem. There is a vacuum hose that runs from the top rear of the Throttle Body Housing Manifold and goes to a unit against the firewall directly in front and above the of steering. After a closer examination this hose had a wear gouge that was caused from rubbing against the firewall lip. I used HVAC foil tape to seal area to test. Cleared OBDII code and test drove about 20 miles drives like it came off the showroom floor.


I will keep you updated when the hose is replaced. No one has mentioned this as a potential problem.


I did not observe any a air noises from the base of the EGR tube via DPFE exhaust manifold. l also I did not know how to check for clogging at the DPFE ports on the tube? If P0401 comes on again after I replace the vacuum hose then I will replace this EGR tube (if I can get it off the manifold!)


Thanks-jmm

 

Ok- the p0401 returned again! Bought a hand vacuum tested egr- almost quit but stalled and lowered idle. With engine off pumped 5hg of vacuum to egr port -removed hose-diaphragm can be heard closing.
Removed "new hoses" from "new dpfe" they had moisture in them. I could feel slight pressure from egr tube ports, also when plugged ends could feel pressure buildup on hoses.
Traced the "red" PCV vacuum hose back to battery tray- splits off and goes under washer bottle the other one goes into firewall under hood bolts on passenger side.
I will receiving a new egr (evr) solenoid to put install.

Running out of parts to install.
Could the dpfe go bad in a week?
Also- once I install the egr solenoid I am going to remove the battery ground and then connect a small jumper from the disconnected ground cable to the positive cable and leave for thirty minutes this is supposed to reset the computer to the default -so it will have to relearn all the driving and shifting patterns again.
Any comments or suggestions would be greatly appreciated.

 

No need, just disconnect the battery for a couple of minutes, or use a scan tool to clear the codes. Either way will reset the learned driving and shift patterns.

 

Recent tests:
DPFE: connect voltmeter to top wire out of three of connector using a paper clip- connected red wire from meter set at 20dcvolts. Black wire from meter connected to negative battery post. Turn key on engine off. Reads 7.3-7.4 volts. Next turn engine on on at idle reads 7.4. Applied vacuum to top of egr valve with hand vacuum to 5-7hg-stalls lower idle the voltage would drop and fluctuate between 3.8-7.5.
How do these numbers compare to others with a 1999 5.4L navigator.

Any other tests For the Dpfe?°


In addition tested vacuum on egr valve engine not running no power-applied 5-7hg - pulled hose off you can hear the pintle pop shut.

 

The Grey/Red wire should read ~battery voltage.
The Brown/White wire is the sensor ground.
The DPFE signal wire is the Brown/Light Green wire.
The signal wire should read ~ 0.3 - 1.3 volts with KOEO.


I'm guessing maybe your reading the voltage on the ground wire?????

 

 

Awesome video!!! So today, my new EVR came and replaced this. Disconnected battery. Drove no code. Next-placed voltmeter on lower (bottom) wire on the dpfe connector. Did not get a good reading 0.01dcvolts with key on engine off (koeo). Next disconnected DPFE connector (removed voltmeter) drove around no code. Stopped turned off engine code popped up. P1401? Not sure if this correct however it stated the dpfe high flow was not operational. Plugged back in and then cleared codes. I have ordered an EGR tube wih new adaptor connector to manifold. And another DPFE. I am getting a slight miss at 2000 rpm and hesitation and stumbling right at 70 mph. I am not sure if the egr would cause this issue. I am thinking cop/plugs. Having the EGR system adjust to rich fuel may have done some damage to the plug gaps causing the cops to work harder-causing them to malfunction?

 

OK-So I took my NAV to local mechanic he replaced the EGR TUBE $170 with part supplied. Drove like a champ yesterday. Today I got a P1406 code- Removed the downstream hose on DPFE there was some water present. Shook out water.


I replaced the DPFE twice with EBAY replacements (non-MOTORCRAFT). Should I go for the MOTORCRAFT -Third DPFE?


As you can see by my post I have replaced all the components in the system except for the PCM and vacuum hoses, and electrical wires and connectors. However I spayed electronic cleaner on connector and applied die electric grease.


Please advise- BTW also changed out the MAF sensor.


This is beginning to not be FUN anymore.

 

That code is a result of one of the tests that the EGR Monitor does. It shuts off the EVR regulator and checks to see if there is any EGR flow. If it detects flow it sets the P1406 code.


Repeat:
The Grey/Red wire should read ~battery voltage.
The Brown/White wire is the sensor ground.
The DPFE signal wire is the Brown/Light Green wire.
The signal wire should read ~ 0.3 - 1.3 volts with KOEO.


If you do the KOEO test, there can be no EGR flow because the engine is off. If the signal wire is out of spec, you could be looking at a defective DPFE or perhaps a wiring/connector issue.


How many volts on your signal wire with KOEO?

 

OK- 0.77
Probed DPFE signal wire- 20vdc setting -ground to battery terminal connector on DPFE. KOEO.
Probed Grey/Red Battery Voltage-got 0.22


Also disconnected vacuum hoses to EVR and inserted a vacuum gauge kept green to egr connected and vacuum source line connected to EVR via hose extensions. Vacuum gauge installed -started truck -read around 18 on the gauge. the vacuum fluctuated around 1200 rpm-dropped about down to 15 then came back up to 18-20. Seemed like there was some hesitation in the engine when vacuum dropped.

 

This is what i'm thinking also or you could have a broken header bolt causing a leak? I'm in the same boat as you and have replaced everything and hoses and the last thing i'm thinking is an exhaust leak or egr tube leak near the manifold. I had a shop last year tell me my exhaust manifold bolts looked pretty rough and would need to be replaced at sometime and then this code started to appear so I went the route of replacing the EGR components with no luck. I'll have to post if I have any luck after installing these new pacesetter long tube headers and egr pipe.