Getting a P0400 code, EGR Flow

[Benfolio]

Need to pick yer guyses brains.

Is it common for the EGR valve to need to be replaced or is there somewhere else I should look first? Maybe it just need a good cleaning?

[decke48]

the egr tube might be carboned up. is it high flow, no flow, or low flow?. you can clean up the egrs with some carb clean, shouldnt nead to replace the egr unless the diapham is broken

[Benfolio]

insufficent flow.... I'm probably just going to take it off and carb clean the hell out of it. Gotta pass emissions soon so I don't want the light coming back on...... although I could just take our scanner with me and hide it in the glove box.... delete the code when I get there :twisted:

[decke48]

there a metal pipe the goes down to the cyl head use a coat hanger to clean any carbon built up in it. when you clear a code all your emission standings go to unready so you have to complete your drive cycles for them to come back to ready. idk how many you can fail in wilwaukee. but here its 1

[Benfolio]

Well it's been off since yesterday, hasn't come back on... yet. If it's still off tomorrow I'm taking it then. Otherwise I have until May 1st.

[immortal1kon]

theres three things you can check or change. the egr valve itself, then theres the back-pressure transducer, and the egr valve solenoid. i have my check engine light on right now becuse of one of those three and i just dont have time to replace them. if you need to know what these parts look like i can send you the legacy manual through aim or something lmk . gl

[Benfolio]

I know what they are and where they are. They look brand new too.
Ugh, light did come back on yesterday, FIVE BLOCKS after I passed my emission test.

Haven't scanned it yet but I'm sure it's the same code.

Will clean it out this weekend.

[pdawg]

What does the egr valve look like?

[Benfolio]

EGR looks good, diaphram is fine, still getting the code. If I clear it it goes away for a few days or more, then comes back.

Hoses and everything look good too.

Was thinking I should swap the EGR solenoid with a known good one and see if that's the problem.

[Benfolio]

Figured it out with a little help from alldata.
There's a conector under the dash that cycles all the solenoids and switches under the hood, so the EGR solenoid was clicking. Warmed up the car and watched the EGR when throttle was applied.
It would open, but not close all the time when the engine returned to ide, causing the CEL and the rough running I get that I mistook for a misfire.
When the EGR was stuck open, I pulled the vaccum line from the solenoid that is supposed to open/close it, and it was constantly getting vaccum at times.
So I need a solenoid. SHould be in Monday, I'll report back if it fixes my problem.

[Benfolio]

Replaced the solenoid and STILL the EGR won't close when the the throttle is returned to idle.

Took off the EGR and it moved freely and holds vaccum, so it CAN'T be a bad EGR.

What tells the PCM to open and close the solenoid?

[Benfolio]

Weeeeelll I'm a retard. Vaccum lines were backwards from day one. Just figured the short line CLOSEST to the solenoid (from the BPT) should have been on the CLOSEST nipple on the soilenoid, and the furthest goes to the EGR.
And that is wrong.

Don't know who did it, but it's fixed now.

Just got to return the new solenoid to the Subaru dealer now...

[Huffer]

Good find!

[immortal1kon]

hey guys i also got the p0400 code and an assortment of random other possible codes. but my problem is that the hose faarthest right on the BPT (which has 2 on the left nad one on the right) well it's not doing anything and thats the hose that feeds the egr to open nad close which it's not doing. can anyone tell me anything aobut an under dash solenoid which i have heard through the grape vines and or any ideas to my fix. is it just a new BPT or whats up thanks a bunch in advance.

[Dead91silvia]

I have been getting a P0400 code for the last few months...
I have looked and the EGR Valve and it seems to be working fine and I have recently cleaned it out (about 15k ago)...

When I got the car running this summer, it ran great, no problems, but one day it tossed up the P0400 code and then the car started to run a little rougher... Still has good power, but sometimes would hesitate like it had a bad injector or or 1 cylinder not getting spark (has not happened for at least a few weeks)

Any more ideas???

[Dead91silvia]

So a while back I pulled the whole EGR system and cleaned the hell out of it. The little steel pipe was plugged solid and so was another passage... I got them all cleared...

After cleaning it all again along with the EGR Valve and clearing the codes, I'm still getting a P0040 (egr).... Just wondering if maybe the EGR valve is toast? I cant think of anything else.... Anyone got anything to add?