The reference voltage sure seems close enough. As for the other voltage, it's probably good. You have two sensors that agree, so my guess would be they are OK. However, I don't have any official documentation. The shop manual I have only refers to the emissions diagnostic manual.

If you doubt the multimeter, by all means go back and check with a known good one. And perhaps you could check the output to verify that voltage varies with pressure.

In an earlier post, you mentioned that there should be 12V to the regulator valve and it should be about 37 ohms across the coil. Did you check this? Also, if it should get 12V, have you applied 12V to it to see if it responds and that you can get flow through it?

 

Reading your description of symptoms made me think back about eight years to when my 99 mustang was throwing the same codes and pinging under moderate acceleration. It was all from a plugged converter, the DPFE code and pinging was from the back pressure and the o2 code was from the converter holding back the exhaust. I was blowing the hose off of the DPFE from the back pressure before I finally figured it out.

 

Its something I have considered. I have been chasing a reduction in gas mileage too. The pinging is coming only after it warms up. When cold it wont do it. Is it possible to inspect the converter to verify?

 

You can check The converter/converters with a back pressure test that requires special tools and knowing the specs, removing the converter/converters and verifying you can see light through them or like I did and know its bad and knocked the guts out and put a 1/2in long piece of flexible copper piping over the end of the rear o2 sensor to make the computer happy. I can't explain why covering the rear O2 sensor makes it work correctly without a converter but it was a crazy idea I had and it worked.

 

so assuming my test on the EGR solenoid comes back good, then the only option to test the cat is just replace it?

 

You can test the mechanical integrity of the converter (did it melt or break up) by checking the back pressure built up in the exhaust pipe by using a fitting into the O2 sensor bung to adapt to a pressure gauge. Run the engine, read the gauge. No (little) disassembly required.
You can test the function by watching the down stream O2 sensor reading or using an exhaust analyzer with probe inserted into the tailpipe of a running engine.
So, no, you don't test by replacing.
This post is so long I don't know what's happening any more.
tom

 

Sounds like something that I cant afford to buy inexpensivly and would have to be taken in to a shop. At shop fees of the test and a cat that costs $100, I would suspect that I would spend as much money getting the system "checked" than I would just replacing it (after physical inspection).


With tone being hard to understand on the internet, im not sure what you are asking here. I started out with codes and a pinging. Done testing and replaced some stuff and not had any changed resultst. So we are exploring other options and discussing them.

 

Nothing meant by the comment except that the original problem and symptoms seemed to be getting buried by all the other commentary and embedded videos. I guess I was looking for a summary of 'where things were' after doing all the above, and did it fix the original problem. It is not you, it is me and my memory or lack thereof. I read so many of these posts I forget what's happening and what the current situation is. Some threads seem to wander so the first thing may be fixed 'but wait there is more...' leading me to wonder(wander?).

I thought of this after post about checking using the O2 port above:
You can connect to one side of the DPFE for access to back pressure information. That is what it measures using a fixed orifice in the EGR tube to know EGR flow. I am pretty sure one of the hoses is exposed to the current exhaust back pressure. Sticking a vacuum/pressure gauge into either hose, one at a time, should give a back pressure reading. I think.
tom

 

Ok cool!

Summary so far.

Was getting pinging under load, CEL came on and stayed on. Codes run were:
P1401 DPFE sensor
P1053 O2 sensor Oxygen Sensor Circuit Slow Response (Bank2, Sensor1)

I cleared codes and the 1401 came back (o2 sensor code did not). I experimented with a new DPFE sensor, no change, so I moved into the EGR system to check that everything was working right.

Those items looked at as part of the EGR system:
EGR valve
EGR solenoid
DPFE sensor

I tested the valve and it appears to not be blocked and worked normal
Need to test the EGR solenoid (my multimeter died)
I tested the DPFE sensor via rockledges page, seemed within proper numbers. Checked the lines were not blocked.

It was suggested it could be a blocked cat. Truck is a 250k mile truck. So anything is possible.

edit: EGR solenoid tested. Seems to be close to the proper number range at 41.5ohms. The number I came up with was 37.2 ohms. I tested putting 12v to it and the solenoid switches. Just finished road test and verified the EGR solenoid is switching and showed change on meter as expected.

 

The problem in this whole thread is one of not reporting codes accurately and too much intervention with other things.
The other problem is no one has bothered to look at the code 1401 description from a good Ford source.
If you did you would have saw a 'circuit high' as the trouble.
It is electrical involving the DPFE not some where else on the motor.
Plugup or harness issue?
It tells you circuit high!
Certainly any DPFE you plug in and test will all look the same until the circuit is repaired.
Good luck.

 

Thanks for your post. I read the circuit high as meaning the DPFE was acting out. You say plugup or harness issue, I understand that the latter you are suggesting its a problem with the wire harness, but unless you are meaning plugup (blockage) of the cat im not sure I understand what you mean.

Suggestions on testing the theory you have put forth?

 

Watch some TV on your computer here:

://www.youtube.com/watch?v=qkgsA4LdEjk
He measures the volts ... and first thinks the DPFE is bad... I didn't watch it all.

Or read some text here, where the words indicate wires or DPFE problems...:

P1401 Ford DPFE Sensor Circuit High OBDII Engine Light Trouble Code | Engine-Codes.com

tom

 

Thank you for the links. I saw the video previously. Problem is he is using a computer that I dont have and it does not indicate how to test to get those numbers without the computer.

The link you provided tells overview of the EGR system, but doest provide any info on how to test.

everything I have tested so far has come up as neg for problems.

Bluegrass suggested that its a "circuit high" and that I have gone the complete wrong direction with my testing, but at this point I dont know how/what else to test.

 

Learning curves are tough!
A 'high' is an open circuit causing voltage to read too high.
A 'low' is a short or voltage too low.
.
DPFE: it is a sensor only and does not control any function directly.
It measures a difference in pressure across a disc hole in the metal tube to which it is attached by hoses and reports the result of a requested test..
It has electronics in it that is fed about 5 volts to ground.
The third connection is the feedback to the computer to readout the pressure difference when the test is called for.
That readout is compaired to a fixed table. Either it is within that tables limits or it is not as a fail result. The tolerance is very tight such that many aftermarket DPFEs are not good enough to use.
.
In the video he shows you the difference between a faulty DPFE and new one by looking at a voltmeter graph on his scanner.
That is no different than using an analogue or DMM meter.
In your case the computer sees the DPFE circuit open hence the 'high' in the description.
Is the feed open?
Is the ground return open?
Is it a bad plug?
Is the feed back getting to the computer etc.
.
You may not think so but these systems never lie about what they are tasked to specifically do, so you can bank on what the code says providing you interpret it correctly and it has not 'cleared' or been cleared at the time you see it..
And they are backed up with live data if using a good Scanner to see the same result in another way.
Another point; if you look at code 0401 and 1401 the difference is the 1 means an electrical fault has been detected. In 0401 it means the flow test failed such that it could be the DPFE or a blocked passage or the EGR did not open from some reason.
Would you begin to see the logic in this so the system can tell you what is likely the 'case' but not the cause because of all the parts in the system that can fail...
Good luck.

 

Or the catalytic converter is plugged causing incorrect exhaust pressure........