First 2 pics are EGR Changeover valves according to AutohausAZ.com. It's located on the back of the engine.

The second two are the "EGR Switchover Valve" located at the front of the engine... (it's the cylindrical canister on the left in the pic that shows the MAP sensor too.)

Which of these is the problem for a P1400 code?

 

P1400 is for EGR transducer mounted on the EGR valve. One mounted next to MAP is for vacuum supply to air injection valves.
.

 

Ok, thank you for the clarification. I'll pull the EGR valve then. I think I'll try cleaning it first and see if maybe there's just some nastiness gumming it up. AutohausAZ.com has the EGR Valve and switch for $113, seems like a better investment than just the switch for $40.

 

Ok, so I tried replacing the valve switch/crossover/changeover/solenoid that was mounted to the EGR valve itself. New part doesn't look like the old one. If you look at the pics above, what I got was the one in the upper left, which looks nothing like the one mounted to the EGR. And it did absolutely nothing to fix the problem or even clear the code (battery disconnected to clear, but it came right back.) I figure the difference in form is that there is a backflow valve between the manifold and the piece I'm intending to replace... am I missing something?


I'm about 50 seconds from dropping a molotov cocktail in the driver's seat and walking away from Mercedes as a brand altogether.

 

I'm about 50 seconds from dropping a molotov cocktail in the driver's seat and walking away from Mercedes as a brand altogether.

EVERY MERCEDES owner / DIY Mechanic has said this, and probably more than once !

Then your Fix goes well, you hit the road, that total command of the road your Benz provides soothes you & all the frustration melts away...and you remember the Molotov with fuse lit is STILL rolling around in the back...pull over & snuff it out...whew that was close !

LOL - David in Texas

 

Don't forget to light the fuse.

 

Ok, so I went back in, pulled the EGR Valve, cleaned it, cleaned the tube again, pulled the throttle body to clean it, and in the process noticed that there are a few damaged hoses going to the throttle body. One of the broken hoses/assemblies is a "coupling" of sorts that "compresses" down onto the TB and the intake manifold. The part that goes on the TB has an inner stem that has broken off inside the TB. Should I even worry about the broken coupling as long as it still seals over the intake ports and the hoses that go into it are intact? I'm grasping at straws here.

 

There could be a leak from your damage description. If that system is not perfectly sealed you
will have running issues and sensors will throw codes.

 

Here's a pic of the piece I'm talking about. The little stem thing goes in the throttle body itself with the tapered end sitting just behind the butterfly valve.

I'm going to mercedes tomorrow to see if I can even replace this part. None of the online parts shops seem to carry it, although I've found lots of other things to attach to the truck... I'm also going to return the valve I got from autohausaz.com and just buy the whole dang EGR assembly. That way I know I've got the right part.

Maybe...

 

Replaced EGR valve/solenoid with known working part. Code gone. Truck still runs like crap. See new thread...

THANK YOU WITEK! I really do appreciate your advice and expertise.

 

Hope that was good for a laugh or two. I'm saying this as I embark upon my first Benz Power Steering Pump R & R. We shall keep a Molotov nearby, just in case !

But seriously I also did an EGR clean & Vac hose replace a year ago, similar to yours.

Ahead of time, I just ordered all the VAC hoses & that little 'Vac Junction Tee' plastic piece you found broken. Pretty crucial stuff !

I wish I had just put a new EGR on. I did clean it thoroughly - the pintle had so crusted up that the Transducer would try to move but couldn't, so it set a code.

So after cleaning it all up & restoring function, I think it STILL needs a new one, here's why:

The little cavity that is supposed to seal off (can't recall if its upon activation or as a resting default position) really doesn't. Yes the Pintle moves trying to do so, but there is so much wear on the piston thingy (technical term) that the seal really doesn't occur. I could see that much by testing it's ability (failure) to hold liquid solvent.

Ok, to my question, if anyone can say: So my 'works electrically, but NOT as a sealed Vacuum EGR valve' unit, could that be the cause of my excessive exhaust smoke that is SOMETIMES coming from the exhaust ?

It is intermittent - not always there, seemingly not with cold engine, only when fully hot and when idling for a decently long period. Then upon revving up & taking off, pretty distinct cloud of darkish exahust is seen behind me.

Oil usage is nil & mpg is pretty good about the same as always.

So, I'm leaning towards ordering the Pierburg new EGR Valve - $95 from FCP Euro, last I knew.

Appreciate any input on this question !

David in Texas

 

David, power steering pump is an easy one ! Just make sure to purge the system after you complete the procedure with turns lock to lock....don't want any bubbles ! Cleanliness is critical and a factory or similar unit with new o-ring......