On my 2001 Ford F150 4.2L Truck I had a “Service Engine Soon” Light. The diagnostic code was P0401.
Insufficient EGR flow. I removed & checked the EGR valve with a vacuum source. The valve was good.
I also checked for carbon blockage. That was ok. I decided to put a vacuum gauge in the vacuum supply line to the EGR valve to see if was getting vacuum as it was supposed to. Here is what happened. When the truck was first driven the vacuum gauge read about 6” hg. When the truck reached operating temperature, the gauge read 0. No vacuum. Any suggestions as to what the problem might be.

 

The EGR system should be inactive when the engine idles...

http://autorepair.about.com/cs/generalinfo/l/bl470g.htm

Apply vacuum to the egr valve and see if it makes the engine stumble or stall.

 

I don't know if it is the same, but the Mark VIII and Crown Vics have some grooves in the bottom of the throttle body that need cleaning periodically. When my Mark gave an EGR code, I took it to the dealer and they cleaned the groove at the base of the throttle body and replaced the flow sensor to fix it.

 

Replaced the DPFEGR Sensor. So far so good

Got it from Ford Dealer
Part No. 4U7Z-9J460-AA for $29.78 +tax

There is another sensor that cost $85 but the
electrical connector won't fit my truck.
Don't know why the price difference, but it sure pays
to investigate.

 

Hmm...

My DPFE part# is F7UE-9J460-AA and is metal. Is yours plastic?

 

Hey guys. This is my first post on here, and it seems to be a great forum for F150 owners.

Anyway, I used to be a technician at a ford dealer, so I have seen these codes hundreds of times (P0401 & P0402). About 95% of the time the DPFE is the problem.

Ford has even issued a service message to techs. that if these codes come up, to just replace the DPFE with no further diag.

One last thing, new updated DPFEs are plastic which replace all metal ones when they go bad.

Later

 

temp1

yes it is plastic, in fact the old one was also plastic

 

wondering if I could get your opinion on 2001 Escort. I replaced the DPFE cause I would get alternating P0401 & P0402 codes. This would solve my problem for 4-6 months and then again would have both codes so installed another DPFE which solved the problem again. Then the same issue many months later and now again this week, so about a total of 4 replacements on the DPFE in the past year an half. Is there something I should check as to why I keep having issues with the DPFE sensor?

 

In 2001-2002, a problem was identified with the EGR valve not operating properly at tempreatures above 105 degrees. I don't know if this has anything to do with your problem, but it might be worth looking at. In Phoenix the outside temp gets over 105 quite often. When it did, and I took off WOT, it just fell on it's face.

 

Oh, I'm so glad you cleared this up for me!!
Ford sold me the small plastic one that will not fit my connector, I have the F7UE-9J460-AA, which by the way, IS made of metal and screws in with two philips head machine screws, the 4U7Z-9J460-AA must just hang there on the vaccuum lines.
Was most certainly for the 4.2 v-6 application.
Now I've gotta convince them it was thier parts guy that made the error then try to get them to take it back since Ive opened the package, stapled it back real nice though..grrrrr