EGR P0401 can't resolve
 

Okay, i'm new to the evo, so bear with me. I recently took delivery on a used MR and starting pulling a P0401 code. For some reason it always reads as two P0401 codes (don't know why that is). Anyways, I know it's a low flow egr code, and i searched the forum and saw the detail on the vacuum lines.

My problem is, I've searched around and felt around, and I'm absolutely positive the two vacuum lines are attached. There is no loose end by the solenoid. In fact I wasn't sure which was the egr solenoid, so I check the metal piece directly below the TB and the diaphragm looking metal piece directly below that. They both have two vacuum lines firmly connected. Is there a third line that I'm missing that could have come off??? Could this code be related to something else? Any ideas would be great. I've reset it twice and it's come back every time. I don't mean to be an annoying newb, but I'm stumped and would really love to resolve this problem myself, cuz that's 50% of the fun and 90% of the frustration of owning a car :beer:

Thanks for the help guys, I'm sure a solution would help about 30 other people too judging by the number of posts that the search pulled up!

bumpity bump. Anyone? :( When I was feeling around, I did notice that there felt like an open port (not a nipple) on one of the pieces, but no loose hose anywhere's in sight. Is it just the two vacuum lines that are supposed to attach, or is there something else? Thanks guys.

What size are the lines that you are looking at? If they are the ones that I think you are looking at, then they are the coolant lines. Reach your hand behind/below the throttle body, but also futher down the intake manifold. There are two SMALL vacuum lines that are attached to each other. A quick feel on those lines may give you the impression it ok. Take your time, don't be afraid to take off the ic flex piece and stut tower bar. Good luck.

-Dave

Ok, i took your advice, but now i'm sort of confused. I thought I was supposed to be looking for the two small lines attached to a metal piece, but I was able to find the small lines that are sort of connected to each other, almost closer to the passenger side than the drivers sider though. I couldn't feel anything loose there, but didn't think I was in the right spot still, so I may have missed something on them. Am I in the right spot? Should it be the two hoses coming off the metal piece below the TB, or the two hoses that are very close together further towards the passenger side and down?

I really would love to get this figured out as I'm supposed ot get inspected soon. Thanks for the helps.

Only one thing then....maybe two...Bad EGR vacuum switching solenoid. Could also be a sticking EGR valve.

Take the valve out and jump the terminals across with a 12 v.
Listen for the click. Then get a vacuum gauge and pull vacuum and see if gauge drops. This will tell you if the valve is either holding or leaking.

I sent you an email regarding what you may want to check since I can't sent PM's on here.

you're the man! I just got your e-mail, my internet's been on the blink too. I freakin found the probem i think though, and it is DEEP in there. There's a small vacuum hose that popped off, but of course it wasn't off the TB where I could reach/see it, it popped off in the dead rear middle of the engine about a half arms reach down. It looks like I will have to pull the strut tower brace and upper IC pipe off to get at it, but atleast the mystery is solved.

Is there anything I should know before removing the strutbar and UIC as far as torque specs or unforseen consequences with the struts might go? I'm pretty fired up just having figured out what the damn problem is though!

I think the strut tower bar brace bolts are supposed to be torqued down to around 30Nm, but I could be wrong on that. I will check my CD Manual for the Evo to get the exact specs on torquing those bolts down...you will need a good Torque wrench...if you don't already have one.

good deal...i'll have to check my car too... i'm getting the same codes... same 2codes

same codes. hopefully a fix. let us know how it goes.

i got mine....i found the hose...if i had a mirror i could see the nipple i plugged it onto...i had to remove my stock upper strut bar...it wasn't that bad...just plugged it back on as far as i could...and thats it...

my issue ended up being a faulty egr valve gasket. I'm having that taken care of today by the dealer. Hopefully that will resolve this issue!

that sux...
...so you never found the hose?