Keep getting code 4 on the regular code reader, which is the EGR code. I had a new EGR tube put in and thought that would end those issues. What could be the problem now ? On the 95 E320.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

That chassis has a TSB Campaign for EGR codes ..the orig EGR shaft was too large and it would stick ...it was re-designed.
I will look that Campaign up for you.

When they had a Campaign, they would change the part when a car came in for service and then mark the new egr with a dab of white paint so the next guy knew it was done..the part # was the same..that's why they dabbed the paint.

But there could be other reasons..so here is the basics :

EGR test is to manually pull >12" vac at EGR port with car @ idle w/hand pump..this will cause the engine to run very rough...if NO, then the port is plugged @ engine or the EGR element is not opening. If YES , then the passages are clear and the EGR is verified opening and tube clear..next test is to see if it holds a vac.... and when you release that vac , you can hear it SNAP shut. Try that snap a few times for hang-up.
The reason for this test ,even tho you had the tube replaced, is b/c sometimes they do not clean out the intake port well where the tube mounts........

IF YES/OK on above, then you have to check that you are getting vac supply to EGR. This is from engine, via an SOV valve [ Switch Over Valve--]..that valve is piggy-backed with the AIR pump SOV under the front engine panel [ top/front] These two SOVs have a single ,white plastic vac feed line from the engine..they are infamous for cracking from heat fatique, so that would be my first check after EGR manual test.
It is also possible [ I have seen this several times ] , that someone has reversed the lines, so check that also.

And finally. there is a small vac pressure sensor that reads engine vac changes and reports this to the Diagnostic Module N/59 [ Emmissions Module].. When the ECU sends an EGR activation electric sig to SOV, It also looks at the pressure signal from the sensor to see if a change has occured...If that sensor is bad /unplugged/cracked vac line /etc.] the DM reads that signal as No EGR activation and pops the EGR code

Thats how it works, and knowing those basics will help you track it down.

If not , post your findings. Or post them anyway....

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A Dalton

Will do my best to follow up Arthur, but your diagnostics are a bit above my capabilities. Will print out your reply, if necessary and forward to my indy. I will bet the problem is fairly simple though. Thanks once again for the prompt reply.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

OK

Before you go to your Indy, I would at least look at the vac line under the front cover b/c that is a very common cause of egr code. ..and if you have a hand vac pump , a quick manual EGR test @ idle will tell you if there is any blockage .

The rest of the stuff is a little tricky, but those two are simple and will tell a lot.
If you do not have a vac pump, you can also simply steal some vac right off that same plastic line ..just run an extension vac line from the end of that over to the egr and see if the engine runs crappy at idle..if yes, you at least know the EGR is working and the tube/port are not plugged.

either way....it is fixable.......

In the event he can not find problem, the Benz EGR Campaign is #95-0131
and the last date code on the EGR is 94T174...anything after date that has the redesigned EGR...look for a Red or White paint dot on your EGR..if Yes, it has been addressed already thru that Campaign.

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A Dalton

Thanks again Arthur,,, will give it a try today.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

How does one tell if the SOV plugs are switched?

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Gone to the dark side

- Jeff

I knew that was next....cuzzzzzzz it's a good question !!!

Couple of ways

Wire colors are:

EGR [Y27]..bk/rd - gy/wt

Air [ y32]..gy/bu - br

There is a pic in the EGR section here:

http://www.peachparts.com/Wikka/M104HeadGasket

..and finally, [ and easiest]..when AIR pump comes ON, see if the EGR vac line is getting Vac..simply pull the line @ egr and put your finger over it to feel the suction.if YES. you know they are reversed .
The AIR SOV is wired to come on WITH AIR pump activation, so if you have vac at EGR w/AIR pump, you know the lines are crossed.

http://www.peachparts.com/shopforum/attachment.php?attachmentid=67045&d=1240263522

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A Dalton