Apparantly there is a way to test the DPFE sensor. Here is a link to an article describing how to test it. (The sensor has to be installed in order to check it):

DPFE Sensor Test

 

Thanks to all the posts regarding the P0401 code and the DPFE sensor. It fixed my problem and more. Great job!!!

 

The best test to detemine whether the DPFE sensor is defective or not is to backprobe the 2 outer wires in the connector w/ a voltmeter. It should read approx. 1 volt KOEO. To clear the dtc, the battery can be disconnected or simply reset with a scan tool.
There is also a Ford program that extends warranty coverage on these. To see if your applicable, call your dealer with your VIN # handy and they can check.

 

Hey 01Ranger,

Thanks for the tip. This might sound like a dumb question, but do you mean to test the connector wires while they are still attached to the DPFE? Or pull the plug off and then check them?

Also, I have attached a diagram of the DPFE connector for reference. So you're saying that crossing the VREF wire with the DPFE SIG wire should result in a reading of one (1) volt? How does that tell us that the DPFE is bad?

I'm just trying to figure this out so I apologize if it seems like I'm quizzing you.

 

Yes, with the sensor connected. It should read 1v if its good. But more than likely it will read around .1-.2 volts. Anything other than1v is considered bad.

 

Hello 2001 Ranger,

Good information as I am considering if I should replace my DPFE sensor or not. Do you happend to know if the extended warranty was through the emmissions warranty or through Ford in general. Just curious... Perhaps it wouldn't hurt for me to swing my my dealer tomorrow and inquire?

 

It's through Ford in general.

 

I had a P0401 code in the Taurus a few times, and didn't bother to care very much. Will replacing the DPFE cause this to go away?

 

I had the same code in my 01. Replacing the sensor fixed it.

 

yes, call your dealer first and see if your car is covered under the program that will extend warranty coverage for the DPFE.

 

Check for plugging downstream of the EGR valve. This picture shows just how bad it can be. Both me (98 expedition) 110k and my brother in law (98 F150) had same problem. Codes showed low EGR flow. Tried all the suggestions first, bought new DPFE switches, Cleaned EGR valve and exhaust manifold tube, etc. All the time it was this simple ugly plugging. Relative easy to clean after removing throttle body.

A business card is inserted in TB so you can see black sludge ball. There are two one for each port and there shadows on the card. Passage ways totally plugged. Used coat hanger to clean.

 

Hmmm, seems to be DPFE night for me.

If you are looking for a good detailed test procedure, and you've not invested $180 for the Diagnostic manual, I recommend Google search "Snap On DPFE test". Something like that. I found a very detailed procedure, right color wire, correct hose.

This is a 3 wire transducer. 1 wire is the 5V reference signal, a ground wire, and the output or variable wire. You put 9" of vacuum on the larger of the two connections, use a voltmeter and read the voltage on the wire with the variable signal, Key on engine off. A very good test procedure. As stated above, a consistent voltage of .1 to .3 indicates failure. Mine was a robust .3. With a discount, Ford gets $62. After market is around $60. The extended warranty on this component is for the 2000 or 2001's, I think that is what the Ford guy said.

Again, download this test procedure from Snap On. I may have mistyped a step or two.

Good luck with this repair.

dlmeyers 99 Ranger 3.0

 

Thanks for the info, and welcome to FTE!

This is the same procecure (and a little more), with a reference to the source you mentioned:

- DPFE Vacuum & Voltage Test

 

I believe I'm having the same problem in my 98 Expedition. Failed emissions and got that error code. Does anyone know a store that might carry the DPFE sensor. I'm having a hard time finding it.

Thanks

Jack Houser

 

Have you tried the Ford dealer, sometimes their prices are OK.