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1999 Mercedes-Benz E320 4Matic
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So I bought my 99 e320 about 2 weeks ago and I of course had all the normal maintenance stuff done... new tires, check brakes, oil change, another oil change because those SOBs used regular oil instead of synth, wash, wax, and good engine degreasing. Car ran great but from day one but CEL was on and car was throwing a P0400 code (EGR) I checked all the vacuum lines, cleaned them out, replaced anything that even looked like it might crack and STILL P0400... so off to the parts shop for a new EGR valve and it needed it bad.. tons of carbon build up and stuck open. Installed the new EGR valve (BTW what a PITA I think engineers sit around coming up with bolt locations just for the sheer joy of knowing someone somewhere is cursing them and busting a few knuckles) Car did run better (Not going through nearly as much gas and a bit more power too) but the dreaded P0400 code remained. Well I know better, you know better and we all should know better but I never bothered to even check to see if the EGR pipe or hose or whatever you want to call it was clogged... Well this morning I pulled that sucker out (BTW another major PITA - who puts a curved pipe in a straight hole) well let's just say if that was a humans artery they would have been dead long ago. It took me nearly an hour to get that thing cleaned out but that was certainly the last remaining issue with the CEL and the P0400 code. Now it took the car about 15 minutes to get used to having working parts but once the idle leveled off this car with nearly 200K miles runs as smooth as the day it rolled of the production line. So just as a Public Service Announcement I will list a few things to keep in mind when changing the EGR valve on the M112 engine:

1. Check the pipe.
2. Take out and clean the pipe regardless of how it looks from the side not inside the manifold.
3. Do not drop any bolts associated with the EGR system.. they are near impossible to replace and you will have to order them.
4. Keep a telescoping magnet on hand for when you drop one of the bolts. (You will drop at least one)
5. When removing the air intake snorkel keep as much of it intact as possible one of those connections is a real pain to get back together once you take it apart.
5. Prepare to scratch your head wondering who thought it would be a good idea to put a bolt directly below the hardest to remove injector plug.

Anyway just wanted to share a thing or two I learned along the way.. I'm sure most of you already know this stuff but I sure didn't think of a lot of it.
 
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