My wife's car has been flirting with the P0400 code for about two years now. Last year, after a good highway run, it would clear itself two days later, and I managed to sneak it through inspection that way. The next day after getting the new inspection sticker, the CEL came on. No biggie, I knew what the issue was.

Well, now the car's CEL does not go off. Looked through MBWorld.org, and found what most thing the culprit may be: A clogged ERG tube.

August 7, 2010:
I cleaned mine out today. Check out how it looked before cleaning....




And for those wondering where it is located on the engine, it is the metalic tube with the accordion portion to allow movement - right next to the air intake plastic tubing:

(Engine has been cleaned since that picture)

I cleared the codes - but light did not stay off for long.


10/17/2010:
Well, the fixing of the clog didn't fully correct the problem. The P0400 error code kept on coming on. It bothered me that I never did fully check the functionality of the valve itself before I put it all back togther.

Today I finally decided to pull it apart again and see if I could find the problem. Pulled the ERG valve off, with the tube attached and blew into the tube to see if it had a good seal. I could blow through a little, but when I opened the valve manually, I could blow though a whole bunch easier. However, I was afraid that I put a whole in the tube when I removed it the first time, and I don't think I did, the air we leaking through were it was suppossed to go though on the valve.

Next I checked the vacuum hoses - I had already replaced several of the hoses because they have become stiff and brittle, and I think I found my issue. I think the first time I pulled the valve off, I did not disconnect the vacuum hose from the engine, and ripped a small hole in it.


Went to Auto Zone, and for $0.96 I got a longer replacement hose. Not quite the right size, but I put a zip tie on it to hold in in place. Put it all back together, reset the code. Hopefully it won't rear it's head again this time, and the car will just need new tires before the December inspection.

Here is a picture of the valve with the way too long vacuum hose.



Cleared codes - but the Check Engine Light came back on the next day.


10/18/2010:
Pulled the EGR valve off last night. Sprayed the heck out of it with some SeaFoam deep penetration stuff - smelled like WD-40. Says it cleans and lubricates.

Anyways - sprayed it all over the valve, tested the vacuum release actuater to make sure it worked, and it did. Vacuum tested it and the valve did move up and down. I zip tied the new vacuum hose in place on both sides this time, and zip tied the connection to the vacuum release thingie (I couldn't get the locking mechanism on it to work right due to breaking a little edge off the connection). Reset the code, but the light came back today... Again.


QUESTIOIN:
Is the valve good if it not fully sealing? I can blow through the EGR tube and, although it is restrictive, I am able to blow through the EGR Valve.

Also - anybody have any other ideas on what could be done to clear this code?

 

I have the same error code. Very informative post but I don't have a solution. Hoping an experienced MB tech can help us.

Both Vadim nor Evosport could figure out how to fix it yet.

 

I kind of was hoping for more comments or.... anything really. I can't really find a straight answer to the leaky valve question I have - so I'm going to go ahead and assume the valve is at fault here.

I'll go ahead and order a new valve and report back if that does the trick.

Please comment or post any ideas if you think something else may help.

Thanks...


EDIT:
I'll do an edit this time as I haven't really done anything yet. I ordered the valve cover gaskets and a new EGR valve (oil is leaking through the gasket, figured I might as well get that job done while I have the intake out next time).

This is a helpful link in detailing the process I'm about to do:
http://www.benzworld.org/forums/w210...ion-error.html

It will probably be October 30 or 31 before I can dive into the engine again. Will try to document and post updates as I go along.

EDIT2: New parts should arrive on Tuesday - I hope to be able to at least change the EGR valve that same night. I hate that I have to "hope", but I really hope that alone will resolve the EGR P0400 issue for me.

 

Robert,

As I have posted before, WE (not me, as I am not a tech nor do I pretend to be) have figured out your car, at least the first step to fixing it. it NEEDS a new engine harness. You know, the harness that was on FIRE once and never replaced or repaired completely!

Not saying that is the extent of your problems, but until you are ready to replace that harness you will fight electrical problems with your car over and over.

Thanks
Brad

 

Ahh...So the wire harness could be the cause for all four codes?
P0106 MAP/BARO CKT (Manifold Pressure Error)
P0400 EGR Malfunction
P0171 System too lean bank 1
P0174 System too lean bank 2

I am getting a dyno done tomorrow in Upland. Hope these codes don't cause my motor to detonate and go kaboom.

 

very well could be.

 

None of that is really helping me guys. Just saying....

 

Well bud you covered most of the basics on the egr... the only other common thing ive seen is the valve on the purge valve unit. They stick all the time most of the time open which would cause it run real rough which you would of noticed but ive also seen them stick closed intermintally... the diaphrams dont tear just stick so they will pass a vacumm test.

also a mafunctioning switch over valve that controls the vacumm to the valve or any leaks in any lines..

also in rare cases if everything eles fail ive see a few.... if the tube is very clogged like yours ive seen the exhaust gasses and carbon clogg up the ports in the heads.. Just had one of these at my shop .. The car when to 2 places and always had the light come back on ... did some checking and testing and found the egr ports in the heads completely clogged got them hot tanked and reassembled and its never run better

Good luck hope you find it soon

 

This is right where the EGR valve sits on? I did wonder about that spot, it looked like there was a little build up in there, but didn't think it would be enough to clog. I'll be sure to double check this carefully next time I tear into the engine.

Thanks for the information - it is very helpful...

 

hey man....sorry for the issues you're having!....once you get it all clean, it'll work like a charm, eh...if the egr tube was that clogged, i'd bet that you need to get the egr breather covers cleaned out too!....good clean vacuum lines are very important ....good luck!

 

I did change out all the breather hoses and connections - and I did push a thin wire down the breather holes - but I'm not 100% that it cleared out a good path. I do plan on taking the breather covers off and giving them a good wash as I got to imagine it looks like crap under there.

In my recent purchase, I did order the valve cover gaskets - so I plan to spend a weekend cleaning all of it, and resealing it all up. Currently I know I am leaking oil through the old gasket.

 

New EGR valve came in the mail today, and I swapped the old for the new one. While the old was off, I sprayed a little of MAF cleaner below were the EGR Valve sits, and jammed a long straw down there in hopes of clearing up any potential carbon clotting. I sprayed a little more MAF cleaner down the hole and then put the new EGR valve on.

In answer to my own question - the EGR Valve does not do a full seal, on the new valve I was still no able to keep a vacuum through the valve itself. The new one does seem a more willing to open than the old one did - for sure.

Cleared the code, and took the car out for a test drive (just to make sure I put it all back together right, and cause I needed TP for the house)....

Here is a pic of the new valve installed.



I will say - I'm still a little skeptical that this will correct the issue - breather covers are next in line, even though I do feel I cleared them with a wire. If the code is still off on Friday - I'll know the valve was the culprit for sure.

EDIT: As of last night (10/27) - no new news to share - car is still in "Pending" mode:



EDIT Again:
Today 10/28 at lunch I read the car codes again. I think I'm in the clear. I had to read the manual to figure this one out.

In the image below, the "E" is solid (E represents the EGR Monitor). The only blinking light is the "2A" which is the "Secondary Air System Monitor" (Whatever that is).

I won't chant victory just yet though - I still want to see a green light instead of a yellow one.

 

That did it. Finally have a green light.


I'd go ahead and say - if cleaning the tube does not do the trick, replace the valve as well. Still a whole lot cheaper than having the dealer or an indie shop do the work.

 

Congrats! and thanks for the post. I will have my tech try what you did to see if it will clear my P400 code as well.

 

I love a good ending. You probably saved some of us some work down the road. I'm surprised to see how gunked up that EGR tube was. I'll keep this in mind and just order a new valve and tube if I ever get that code.

 

most times it is just the tube that needs cleaning.The op had an extreme case

 

hey man....right on!....glad you got it sorted out, hope that does it for you! .... given the condition of your 'original' egr tubes and subsequently the valve, i'd bet your throttle body and intake manifold are gunked up too!...when you get around to cleaning out the breather covers, take out the throttle body and give it a good cleaning too....good luck!

 

so would a clogged tube cause engine surging? or should I just get a new EGR valve

 

In my experience, the engine never ran abnormally. The clogged tube needs to be cleaned out, and you might as well try cleaning the tube and valve first before you start buying parts. When I started researching this issue, many said cleaning the tube was all that was needed. My case seemed to be a little on the extreme side.

For reference, the valve is about $120 and the tube is about $80. You can easily clean the tube if you pull it out and save the $80.

Also - I will add, I have heard other say that you can clean the tube without taking it out at all. I can't speak much for this method, since I got really good at actually pulling it out. But the idea is the make a small hole in the tube and then spray MAF cleaner in the little hole. When done, plug the hole. Again - I actually pulled mine out, so I don't have any personal experience with this method.

 

Great! Thanks for the info, I will try the clean first. With 200k+ miles, I'm sure it will look gross and need a good cleaning.

 

Hello newbie from uk saying hello I have got e320cdi which started to puff out black smoke on accelaration My indie mercedes mechanic bypassed this valve if you look on uk mercedes owners club you can get advice on bypasing the valve end of problem full stop hope this helpd derek

 

I could not find anybody who did a bypass or delete for the Gasoline V6. I was trying to figure out what to do next if replacing the valve did not clear the code but I could not find a delete DIY or kit for the V6 Gasoline engines. But I am curious if anybody has done an EGR delete on our engines none the less.

The other issue is if the inspection shop figures out that I have deleted the EGR system, they would fail the inspection on the spot. Given where the EGR valve is located, it would not likely be discovered by the tech at the Good Year shop I take my cars to.

 

Has the code ever surfaced again 0r did this fix the problem permanently?

 

Wacheepatos's car got totalled a last year, but I don't think the error ever came back.

 

Sorry to hear about the car. But glad to hear about the code staying off. I think I may have the same problem on mine.