1999 E430 187,000 miles

Driving to work yesterday I got my first Check Engine Light ever(excluding loose gas caps.) Took it to AutoZone and they Pulled P0400 EGR System Fault. My immediate thought was to price a replacement EGR valve... they don't carry it. After looking around the forum it seems my problem could be the EGR Pipe? This is the first time I've actually had any work to do on her (after driving W126, W124, and W140s that required weekly if not daily repair to stay on the road.)

Any hints on getting to the pipe to clean it? location, other possibilities, helpful hints.

After farting around with it for a bit I got the EGR pipe pulled off and it is kinda nasty. Not as plugged as some of the pics I've seen on here though, it passed the blow test seemingly fine. I'll get a picture of it before i clean it up here for good measure, but I'm thinking this probably wasn't the problem. Any ideas what else to check if this turns out not to be the problem?

Look at some of the old posts by Arthur Dalton on troubleshooting and repairing the EGR system.

Here is a paraphrase:

You must check all the components of the system: the valve itself, the wiring to the SOV that sends the vacuum signal to the EGR diaphragm, all the vac tubing in between, etc.

You already cleaned the pipe. Also make sure the port in the throttle body or the intake manifold (at the end of the pipe) is also cleared out good.

Take the EGR valve itself off the exhaust manifold and clean it out good. Clean the valve seat and plug with solvent to get out all the carbon (watch out, messy job). Stroke the valve open with your Mityvac and while it's open blast the valve seat with solvent. Use your MityVac to apply a vacuum to the diaphragm to make sure the valve is stroking properly and fully, is not sticky or stuck, and to make sure the diaphragm holds vacuum and isn't leaking off.

Check all vacuum hoses and fittings in the entire EGR system for leaks, cracks, missing, etc.

Connect your MityVac to the vacuum outlet of the SOV that goes to the EGR (SOV aka switchover valve - a solenoid-operated valve) that sends the vacuum signal to the EGR valve, start the engine, and see if the SOV is opening when it is supposed to. If the SOV opens, you will suddenly see full manifold vacuum (like 25" Hg) on the gauge of the Mityvac. The SOV only opens on certain RPMs and/or certain conditions of engine temperature. You will have to read up to see where that happens. It is probably in the shop manual or in the WIS.

Lotsa stuff to check here... hope that gets you started. The EGR system is a symphony of a lot of separate parts and systems all working together, a malfunction of any one of which will render the system knackered. It is a process of logical elimination: for example, if the EGR valve holds vacuum, the valve is clean, and if it strokes properly, then you know you must continue checking further upstream in the system.

This process may take awhile (like days) because you have to check one thing, clear the CEL/trouble code, and drive the car to see if the CEL comes back on and the code reappears. It was taking my car 5 days for the CEL to come back on after I had cleared it. The pros probably have some way around this but I don't know what it is.

Make sure you read Arthur's posts; he knows WAY more than I do and I left out a lot of necessary information. I used his posts and the above procedure to ascertain that my pipe was stopped up and the port in the throttle body was also stopped up. Pete

Got everything put back together. No access to a speedometer cable but i think I got it scraped out pretty damn good with carburetor cleaner and a clothes hanger. I'm sure this probably won't solve it... I'm just never that lucky, but if by some miracle the issue is resolved, will the CEL off by itself or must it be cleared?

Well on my car the codes must be cleared manually. I think your car is OBDII based on the year and the type of code you lsited. I'm pretty sure it has to be cleared manually also. Take it back to AutoBone and see if their code reader will clear it for you.

BTW you can get an El Cheepo generic speedo cable from AutoBone - they are like $7. Just get a universal one or one from a Ford F150 or something that is cheap. Punch it up on AutoBone's website.

Cleared the codes out and the CEL came back on 30 minutes later. Today after changing the oil i noticed a very loud vacuum leaking sound. Sorry I don't have a camera to show this better.... The front of the engine there two vacuum hoses coming out of the lower part of the intake manifold which go into a sleeve together and come out and into two separate stitch things.... The one on the lower right has semi disintegrated at the connector. Will replace tomorrow and see where it leads me...

Sorry about the lack of knowledge on the terms here.... W126s are more my speed. Luckily this is the first headscratcher I've had with the W210.

Pictures!
This is what the loud(now replaced) leaking vaccum hose was connected to. Any Idea what this is?


Cleared the codes and have yet drive it enough to trigger the CEL again.