EGR CODE???

Hey everybody! I am brand new to this forum, so please bare with me.

I desperately need some help figuring out how to get this code to stop coming on! It is CODE “P0401 EGR insufficient flow detected”. And I ONCE got the “P1409” code, as seen in attached pics. But I have never had that code return, after clearing it. And that could’ve been because I had vacuum lines disconnected at solenoid, when I was doing the test of sucking on the tube going to EGR? I can’t remember if that code came up when I had engine running and was doing all that messing around or not. But I figured I would include it, just in case it helped someone help me. Lol

So after doing some research, I disconnected the vacuum line going to the EGR and I sucked on it, to act like vacuum and it instantly made the engine die, while idling. Which I thought would mean that the EGR valve IS working and that there is no holes in diaphragm or anything. Because in my research, it said that if you suck on it/ apply vacuum to it, and it makes your engine die, it IS working. SO, I replaced the solenoid and cleared codes. Well, even with the new solenoid the same code came up again, within 10 minutes of driving. I’ve cleared it a couple times since then and it just comes right back.

so, outside of replacing the actual EGR, I am at a loss. And I really don’t want to do that, if it won’t resolve the issue. I am not into just throwing parts at anything and always like to be as confident as I can about a diagnosis, before making any repairs. I do HVACR for a living, so I troubleshoot, diagnose and repair equipment all day every day and I am the same way with my work.

So, Can any one PLEASE help me to determine what else could be the problem and/ or what I can do to resolve this problem? I am most definitely not getting as good of gas mileage as I used to (which was never “good” to begin with, in this gas guzzler! Lol) and it definitely seems to not be running as smooth as it used to and even seems to idle a little higher than normal sometimes?

any and all assistance will
Be greatly appreciated! Thanks in advance and God bless!

Jason, what year, engine size, helps narrow down diagnosis. You might want to check if vacuum is going to EGR valve. Also best to use a hand held vacuum pump attached to EGR valve nipple once hose is removed.

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Sorry about that, see? New to this. It is a 1999 Ford Expedition XLT w/ 5.4L engine. Thanks!

Also, doesn’t the vehicle only send vacuum to EGR while driving and under load? So, no way to really check that or signal to solenoid, while truck is just sitting idle? That’s what I’ve been told anyways. So if I’m wrong, please tell me? Thanks!

Hey Jason, here's something I tell everyone with that code with an old Expedition... remove your throttle body and check your 2 EGR ports inside of the throttle body. If you've never done this before, with your truck being as old as it is.. I'm betting these holes in the throttle body are FILLED with carbon. Here's what it should look like with your throttle body off.

46796d1309139195-insuffcient-egr-flow-p0402-problem-solved-0626111803.jpg

Get a pick, carb spray, and some shop towels and go at it. Compressed air will help get all the bits of debris out but not necessary if you're flushing it with carb cleaner or something.

I have actually cleaned it once before, but that was a good 6-7 years ago. So it is very possible that it is clogged again! But wait, Looking at that picture, I don’t remember cleaning that part of the throttle body. I just cleaned the inner part with the mechanical disc that opens and closes, etc. I had no idea that could cause this code and issue! Thanks so much for the info and advice and I will be cleaning my throttle body today. I’ll let you know if I solves the issue.

Jason_parks said:

I have actually cleaned it once before, but that was a good 6-7 years ago. So it is very possible that it is clogged again! But wait, Looking at that picture, I don’t remember cleaning that part of the throttle body. I just cleaned the inner part with the mechanical disc that opens and closes, etc. I had no idea that could cause this code and issue! Thanks so much for the info and advice and I will be cleaning my throttle body today. I’ll let you know if I solves the issue.

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Yes, it's very easy to miss those 2 small ports at the opposite end of the butterfly plate in the throttle body. If it was just the butterfly plate and shaft you cleaned then most likely you'll see solid black build up in the 2 holes.