I know this is probably the 1000th time this problem has been posted in here, but I think one thing makes mine different- No DPFE sensor..

I have a 2001 F150 XL with a 4.7L 8cyl and am getting the infamous P0401 error code. I know the common fix is to clean out a coked up DPFE sensor- I have been reading the posts in here too trying to find a solution that works, but here is the hitch.. mine has no DPFE sensor. My EVR is piped straight into the throttle body/upper intake manifold with a red tube and the green tube goes straight to the EGR.. dunno if this is some wierd variant for Calfornia vehicles or what, but this is shown to be the proper routing on the VECI label too.. I have done the usual "throw parts at it" fix, and needlessly (in hindsight) replaced the EGR and EVR on some bad advice from a friend who is into fords, but this hasn't stopped it from throwing the code. I am done buying parts till I can get pointed in the right direction towards a fix for this problem. For what its worth I also read the posts about disconnecting the EGR valve and operating it manually with a vacuum pump to see if the engine stumbles or not.. result was that mine stumbled pretty hard when I manually opened the although I couldnt get my cold engine to die, just stumble hard. All that having been said, anyone got any other ideas to get me pointed in the right direction with this?

 

I have done some research on both the 2000 and 2001 model years. The systems are the same for both years. The 2002 system has some hardware changes but still works the same.
The code 401 is a low flow detection in all versions.
There is no version without a DPFE, that I have found.
The DPFE is piped off the EGR to the manifold vacuum side of the EVR.
The DPFE reports directly to the PCM.
In the two versions of this system, the calibrated oifice is in different locations, that measures the flow and reports the result.
Also one version has the DPFE and EVR all included in a module called an ESM.
You may have obtained the wrong replacement parts for the version you have.
Not having a DPFE is suspect as far as I can determine.
If you truly donnot have it and the decal says the same, then you need to find that special source of information that covers your version because it is not the more standard version used.
The EVR is pulsed by the PCM at a high and low duty cycle.
It is the low duty cycle rate that is failing, producing the code 401.
In one version, the EGR has the orifice at the intake manifold side. The other version has it on the exhaust side.
The other possibility is the truck was brought into your state from another location that didnot require CA. emmisions standards to me met.
As you discribe the system, it works like the old 5L OBDI systems with the 2 diget codes.
Good luck and let us know how you finally resolve the problem.

 

There's the problem. You have a dodge engine.

 

I think this is the same thing I am up against. I have a green vac line from the EGR to the EVR and then a red vac line to the manifold. No DPFE? Or maybe I have the ESM as suggested. Did you sort out your problem?

Stan