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P0400 EGR flow malfunction


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21 replies to this topic

#1 1-3-2-4

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Posted 25 June 2012 - 11:50 AM

I just had this code pop up anyone know what could cause this? I assume it's some type of blockage?

#2 ocei77

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Posted 25 June 2012 - 01:32 PM

There is a small metal tube that goes from the BPT(back pressure transducer) that feeds the EGR. This gets blocked by carbon buildup.
Clean with a stiff thin flexible wire and carb cleaner.
Alternatively you can remove pipe ( use PB) and soak in gas, 12mm bolt and has a fitting similar to AC.

O.

#3 gavinl

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Posted 25 June 2012 - 08:02 PM

I just had this code on my Leggy with EJ22, it was a torn EGR diaphragm

Replaced with a used junkyard part and all's good ;)

#4 Fairtax4me

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Posted 25 June 2012 - 11:40 PM

You can test the diaphragm of the EGR valve with a vacuum pump.

Sometimes ports in the valve will clog, sometimes it's the passages/tubing leading to the valve that clog. Most of the time it can be cleaned with a solvent and a small bottle brush or pipe cleaner (the metal kind)

#5 ferret

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Posted 26 June 2012 - 06:49 AM

I use my years and a vacuum gauge to troubleshoot this code.

With the engine warm and running, from under the hood, hit the gas for a few seconds and LISTEN, you should hear a 'click' from the EGR solenoid mounted right below the back pressure transducer. Then see the EGR diaphragm move.

No click, then I would put the vacuum gauge right there, ensure you have Ported vacuum coming to the solenoid, and AFTER when you hit the gas.

From there it goes into the Back pressure transducer. If it is present coming in, but not out DOES NOT mean the transducer is bad, it could be a clogged line from the exhaust to the bottom, OR full engine vacuum missing from the 4th port on it.

If there IS ported vacuum coming thru the transducer when you hit the gas, then the EGR itself it the suspect. It could have a damaged diaphragm or just STUCK. In this case I take it off and clean the pintle on the tip.

Only saw 1 stuck in all the years I have worked on these. A few defective EGR's, and many clogged tubes and defective solenoids.

#6 1-3-2-4

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Posted 26 June 2012 - 08:50 AM

I have to go out and check again but in the quick check I did opening the EGR the car would want to stall out.

I don't remember if I have a click or not but my exhaust is so loud right now I might not be able to hear it.

#7 ivans imports

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Posted 26 June 2012 - 11:17 AM

had thiss twice thiss week its the plastic diafram egr controler valve above the egr has 3 lines on top and one on bottom the diafram ruptures and will not hold vacume suck on the bottom line if holds ok if leaks no good i think its from mostrue geting in and freezing in winter

#8 1-3-2-4

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Posted 26 June 2012 - 01:09 PM

had thiss twice thiss week its the plastic diafram egr controler valve above the egr has 3 lines on top and one on bottom the diafram ruptures and will not hold vacume suck on the bottom line if holds ok if leaks no good i think its from mostrue geting in and freezing in winter



You are talking about the back pressure transducer then?

#9 afterbang

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Posted 26 June 2012 - 05:37 PM

when i was gathering information to fix this code on my 98 outback, i read that the solenoid can be the problem, the egr pipe along with all the rubber lines can become clogged with carbon, the egr valve itself can be clogged up with carbon, or the BPT valve needs to be replaced.

I had the same exact symptoms as you were where if you manually opened the EGR valve the engine would want to cut out. this made me think that exhaust gas is getting to the valve itself since it dies as if there is a vacuum leak. this lead me to believe that it was either the solenoid or the BPT valve. A board member here was nice enough gave me a used BPT valve and some silicone hoses to replace the three hoses that connect to the BPT. We reset the code for the 25th time and it hasn't come on in over 3,000 miles and I was able to pass the emissions test. Before, the light would come on in under 50 miles.

I would try a new or used BPT valve and replace the lines if you can confirm that the solenoid is functioning correctly.

#10 1-3-2-4

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Posted 26 June 2012 - 08:01 PM

I haven't had the light come back on yet but I can check the pipes but i don't think I have anything small enough to clean it out

#11 ivans imports

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Posted 27 June 2012 - 09:23 AM

Ya that thing anyway the silacon diafram inside it gets holed and whont hold vacume

#12 1-3-2-4

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Posted 17 August 2012 - 11:55 AM

While I haven't had this code come back yet the lines that you say to clean are the rubber lines? I have some mineral spirits here is that ok to use to clean? I've never seen a brush small enough that would fit those lines.

#13 Fairtax4me

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Posted 17 August 2012 - 04:03 PM

The vacuum tubes (small rubber lines) don't clog. If they split/break you just replace them.

The large copper ( I think) pipe that runs from the back of the head up to the back of the EGR valve is what I was referring to.

#14 1-3-2-4

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Posted 17 August 2012 - 08:11 PM

The vacuum tubes (small rubber lines) don't clog. If they split/break you just replace them.

The large copper ( I think) pipe that runs from the back of the head up to the back of the EGR valve is what I was referring to.


ahh crap I hope not.. I used a flare nut on the one nearest the EGR and it was starting to round.. I just know when I did the HG's that I ended just taking it off from the head instead..

I haven't tried heat but I don't think I can squeeze a flame in that area last time I looked.

#15 Fairtax4me

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Posted 17 August 2012 - 11:18 PM

You need a really good flare nut wrench. Or vice grips.
And a hammer.

#16 1-3-2-4

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Posted 17 August 2012 - 11:46 PM

You need a really good flare nut wrench. Or vice grips.
And a hammer.



I have a really good flare nut wrench :P

I might try the vice grips might not do it until Monday.. Funny how it always rains on the week on my vacation but when it's over it's sunny the whole week?

:Flame:

#17 Fairtax4me

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Posted 18 August 2012 - 12:00 AM

Snap-On? Matco?
I have a set of Craftsman flare nut wrenches that are miles better than the cheapos I bought at Autozone years ago. Yet they're still no comparison to the Matco wrenches I bought last year when I needed good wrenches for brake lines. I have yet to round off a flare nut when using the Matco wrenches.

#18 1-3-2-4

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Posted 18 June 2014 - 09:07 PM

This code is back and the car has a huge loss in power and sucks up fuel in the process I can hardly get 200 miles from the tank at the moment.. I have this and the P0325 code.. I cleaned out the pipes in I think early Dec or late Dec.

 

Can't be clogged up already.. I remember I cleaned out everything because I took the IM off to powdercoat it and cleaned all the lines.



#19 ocei77

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Posted 19 June 2014 - 05:24 PM

Does the egr valve move when you rev it? That little hole gets a lot of build up. And also the hole inside the egr where the egr pipe joins the egr itself.

If you need to remove the egr brasstube , you should be able to just break it free with visegrips. If you need complete access. First, remove the egr itself , then doubling up on the nuts and turning the inner one, the mounting studs will back out giving complete access on the egr pipe.

 

O.


Edited by ocei77, 19 June 2014 - 05:26 PM.


#20 1-3-2-4

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Posted 20 June 2014 - 09:31 AM

yes the EGR moves when I rev i, last time I cleaned it the pipe that goes to the BPT was the one that was clogged and not the copper pipe to the head.



#21 johnceggleston

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Posted 20 June 2014 - 11:43 AM

the car has a huge loss in power and sucks up fuel in the process I can
hardly get 200 miles from the tank at the moment.. I have this and the
P0325 code

not sure about the fuel consumption,

but the loss of power is due to the p0325 knock sensor code.

replace it with a cheap one from ebay, $15 shipped.

 

but if you are in a hurry,

buy it from a US seller, not china.

although the last one i bought came from china? in about a week.



#22 1-3-2-4

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Posted 20 June 2014 - 01:00 PM

The funny thing is the one that's on the car now was one from ebay about 2 years ago.. I had a new one still in the box from ebay until about 2 months ago I installed it on this women's car..

 

I have my doubts about how long these ebay sensors last.. and before anyone asks yes I installed it in the right direction.. it's only because part of the metal casting is higher in that spot (that's why the sensor slopes upwards)






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