So I'm confused on how I'm getting these two codes together consistently even after clearing codes. Ones insufficient EGR flow detected and of course the other is excessive flow. I've put in 2 different diff feedback sensors in and get the same codes

 

P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0402 Exhaust Gas Recirculation Flow Excessive Detected

I would think the EGR Valve is sticking, clogged up
Possible its the EGR solenoid but long shot on that

The DPFE sensor is what computer uses to "see" the exhaust flow, so don't shoot the messenger

Computer uses the EGR solenoid to send Vacuum to the EGR valve
As the computer changes voltage to the EGR Solenoid more or less vacuum goes to EGR valve

The DPFE sensor is connected by two hoses on the EGR pipe, one closer to EGR valve one farther away, the difference in pressure between the two hoses tells the computer how much exhaust is flowing into the intake thru the EGR Valve
Its actually pretty precise way to do it

If EGR valve was sticking then you could get both codes, as the EGR flow is not responding exactly to the computers change in voltage to the EGR solenoid

 

Very informative. However I still am not grasping it. If the dpfs tells the computer the amount of gasses flowing wouldn't that make it responsible for saying if it's excessive or insufficient ? Your answer was in depth and I do believe it I'm just trying to grab an understanding of it fully so I can use that info someday again.

About the valve sticking. I have hooked up a vaccum pump.. or I guess a brake bleeder to the valve and pumped it at idle and of course the engine acts like it is ready to kill itself until the vaccum is released. Wouldn't that mean the valve shouldn't be sticking?

 

Yes, DPFE is just the Feedback sensor for EGR Valve's position, no direct control

Computer bases EGR Valve's position based on DPFE pressure, and it adjusts the voltage to the EGR solenoid(vacuum) accordingly, to open the EGR valve a bit more or close it a bit more

To have just one code, low or high, could mean the DPFE sensor is failing, but if there is both low and high the DPFE sensor's pressure reading must be changing, so most likely it's working


Exhaust has water vapor in it, its why exhaust systems rust from the inside out and why tail pipes drip water
DPFE sensors sample exhaust gases/pressure on the two hoses
The water vapor will effect the pressure chambers in the DPFE over time, which is why swapping out the DPFE sensor often solves EGR system issues
So not a bad guess with any EGR code

Anytime you have trouble codes you need to look up the codes on a full list
Ford Code list: https://www.therangerstation.com/tec...II_codes.shtml

This tells you what codes the Computer can CHOSE FROM, what code best suits the current issue, computer is not smart, each code just has "boxes" to tick, most "boxes" ticked sets that code, lol
Some of the EGR codes:
P0400 Exhaust Gas Recirculation Flow Malfunction
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0402 Exhaust Gas Recirculation Flow Excessive Detected
P0403 Exhaust Gas Recirculation Circuit Malfunction<<<<<<<<<
P0404 Exhaust Gas Recirculation Circuit Range/Performance<<<<<<<<<<<

P1400 Diff Pressure Feedback EGR Circuit Low Input<<<<<<
P1401 Diff Pressure Feedback EGR Circuit High Input<<<<<<

P1403 Diff Pressure Feedback Sensor Hoses Reversed

P1405 Diff Pressure Feedback Sensor Upstream Hose Off/Plugged
P1406 Diff Pressure Feedback Sensor Downstream Hose Off/Plugged
P1407 Exhaust Gas Recirculation No Flow Detected
P1408 Exhaust Gas Recirculation Flow Out Of Self Test Range
P1409 EGR Vacuum Regulator Solenoid Circuit<<<<<<<<

Anytime you see "Circuit" in a code definition, it refers to an electrical signal
In this case you got conflicting "circuit" issues from same sensor, low and high, so most likely not a "circuit" issue because its changing, so you look to mechanical issue that would cause the sensor to have a conflict

 

That makes a lot of sense. So that really just leaves the value. I know atleast Suspect the vaccum solenoid is working since I'm getting vaccum. Only idle issue is I believe a leaking brake booster diaphragm because when I press on my brakes at idle my rpms will raise slightly then drop. I thought the valve was working since I hooked the pump up to it and applied vacuum and it opened up causing very shaky/rough idling until I released it. Could connection between the intake and EGR leaking cause this? Regardless of that I suppose the EGR could still be sticking or not getting significant vacuum when being told to open...parts are cheap enough. I'll check that page out and start trouble shooting

 

For the power brakes
When you get in to start the truck after its been sitting over night, is the brake pedal hard to press, before starting, if so then booster is leaking

Also start engine, count to 10
Shut engine off
Press brake pedal down 3 times, should be easy to press 3 full times then get harder to press as the vacuum in booster gets used up
If that happens this is a slow leak and should cause RPMs to go up
If it gets hard to press after 1 time then bigger leak

 

Yeah roughly I'll get 2-3 pumps before it hardens. As for the sitting over night I can fully recall. I know it has but I feel there were more times it wasn't hard after sitting over night.but yeah if engine is on and at idle if I pump the brakes rpms raise maybe a couple hundred for a second or so then drop back. I have no room guage in my ranger so can't tell for sure