PO401 EGR Pressure Differential

[DirtRider031]

My check engine light came on and i pulled a 401 Insufficient exhaust gas recirculation. I figure its likely the sensor but i wanted to check out everything else. What can all cause this? Should i pull off the whole egr solenoid and the works as i imagine anything can cause and difference in pressure other then what the ecu needs, what should i all look for? The other thing i wasn't sure about is how does the sensor read a difference in pressure if both lines are routed to the same place only 4 inches apart?

 

[Wicked_Sludge]

there is a "metered orifice" inside the EGR tube, between where those two tubes attach. this is where the pressure differential comes from.

i would start by removing the EGR valve and cleaning the valve and all associated passages....this is the most common problem and its basically free.

 

[mdub]

what is the best way to clean?

 

[Southern3.0]

Carb cleaner and a small brush.

 

[John Axtell]

My check engine light came on and i pulled a 401 Insufficient exhaust gas recirculation. I figure its likely the sensor but i wanted to check out everything else. What can all cause this? Should i pull off the whole egr solenoid and the works as i imagine anything can cause and difference in pressure other then what the ecu needs, what should i all look for? The other thing i wasn't sure about is how does the sensor read a difference in pressure if both lines are routed to the same place only 4 inches apart?

I just finished dealing with this myself. Here is how it went for me.
Being somewhat anal and cheap I tend to do the simple and cheap things first.
1. Check all hoses involved for cracks holes etc. There are two hoses that go from the EGR tube to the DPFE sensor and they hidden somewhat and subject to heat.
2. Check to see if the EGR valve is at least going up and down. This is best done with a handheld vacuum pump/brake bleeder. If you use a vacuum pump you can also see whether the EGR diaphram is holding vacuum. No pump?
Okay no problem, do this. Remove vacuum line from top of EGR and put on another piece of hose with a clean end for you to suck on. With the truck at idle (cold engine) give it a good suck. If valve is working the engine should sputter and die, or almost die. If nothing happens and the EGR valve seems to be going up and down there is probably a blockage.
At this juncture you have a choice. If you detect a blockage (sucking doesn't cough engine out) or a partial blockage ( Just a bit of hesitation) you probably have carbon blockage.
To clean. Remove EGR valve, EGR tube (bottom nut on exhaust header is a real bitch but it will come off with enough swearing) and throttle body.
There is a passage for the exhaust gas between the EGR valve and the intake header. Get a bunch of tools like different sizes of wire and commence to clean and chip all that carbon out. It a real pain. I found that an old speedometer cable worked great. Next is the EGR tube Right in the center of the damn thing, between the nipples for the DPFE hose is a restriction or orifice that also gets gunked up. It has to be all cleaned out. Blow some air through to make sure it is all clear.
Now, put it all back together. Reset the codes. Disconnecting the battery for a few minutes will do it.
Hopefully, it's fixed and the CEL will not come back on. So far though it hasn't cost anything.
If the light reappears I would try replacing the DPFE sensor. It's about $44.00 at Advanced Auto or on the internet. If you really like your Ford dealer and want to help him put his kids through college you can give him $136.00 for the same part.
While I was playing with this I did a bit of research. It seems Ford has a real problem with theses DPFE sensors. It is the number one cause of EGR problems on both trucks and the Taurus. Carbon build up is the second cause. Oddly enough the EGR sensor itself seems to be the strongest component.
Hope all this helps. Good luck
PS In the end it was the DPFE sensor on my Ranger.

 

[DailyDriver]

I just finished dealing with this myself. Here is how it went for me.
Being somewhat anal and cheap I tend to do the simple and cheap things first.
1. Check all hoses involved for cracks holes etc. There are two hoses that go from the EGR tube to the DPFE sensor and they hidden somewhat and subject to heat.
2. Check to see if the EGR valve is at least going up and down. This is best done with a handheld vacuum pump/brake bleeder. If you use a vacuum pump you can also see whether the EGR diaphram is holding vacuum. No pump?
Okay no problem, do this. Remove vacuum line from top of EGR and put on another piece of hose with a clean end for you to suck on. With the truck at idle (cold engine) give it a good suck. If valve is working the engine should sputter and die, or almost die. If nothing happens and the EGR valve seems to be going up and down there is probably a blockage.
At this juncture you have a choice. If you detect a blockage (sucking doesn't cough engine out) or a partial blockage ( Just a bit of hesitation) you probably have carbon blockage.
To clean. Remove EGR valve, EGR tube (bottom nut on exhaust header is a real bitch but it will come off with enough swearing) and throttle body.
There is a passage for the exhaust gas between the EGR valve and the intake header. Get a bunch of tools like different sizes of wire and commence to clean and chip all that carbon out. It a real pain. I found that an old speedometer cable worked great. Next is the EGR tube Right in the center of the damn thing, between the nipples for the DPFE hose is a restriction or orifice that also gets gunked up. It has to be all cleaned out. Blow some air through to make sure it is all clear.
Now, put it all back together. Reset the codes. Disconnecting the battery for a few minutes will do it.
Hopefully, it's fixed and the CEL will not come back on. So far though it hasn't cost anything.
If the light reappears I would try replacing the DPFE sensor. It's about $44.00 at Advanced Auto or on the internet. If you really like your Ford dealer and want to help him put his kids through college you can give him $136.00 for the same part.
While I was playing with this I did a bit of research. It seems Ford has a real problem with theses DPFE sensors. It is the number one cause of EGR problems on both trucks and the Taurus. Carbon build up is the second cause. Oddly enough the EGR sensor itself seems to be the strongest component.
Hope all this helps. Good luck
PS In the end it was the DPFE sensor on my Ranger.

Excellent writeup. I never would have thought about the passage from the EGR to the intake. When I checked it, the passage was so badly blocked you couldn't shine a light through it.

Also, the little trick with sucking on the hose to check the EGR valve was sweeeeet!

I changed the DPFE first & was still getting a CEL. Cleaning the passage did the trick. Wish I would have done it first before buying a FoMoCo DPFE @ $135

 

[dorman68]

there is a "metered orifice" inside the EGR tube, between where those two tubes attach. this is where the pressure differential comes from.

i would start by removing the EGR valve and cleaning the valve and all associated passages....this is the most common problem and its basically free.

2X - I agree