I recently purchased a 1994 E320 sedan with a 3.2L DOHC motor. The car ran perfectly for several month's and literally out of the blue began running horribly. I had it towed to the local dealer which informed me the engine harness and spark plugs were "coding", as the spark plugs were not the proper ones for the vehicle and the harness was damaged and had been repaired at one point. I had the harness replaced and the car tuned-up, fluids etc., and everything else checked out as new or in "new" condition. Within 24 hours the check engine light came on again and the dealer retrieved codes number 005 and 008, from the computer but stated that they were not "actively failing", only intermittant, and were old "stored" codes. The car runs very well, but appears to run a bit hotter than before (inbetween the line above the line marked 80, and before the the line approaching the red zone) I've read the posting on the egr valve and testing there-of, but how do I diagnose and where is the temperature sending unit (008 I think), and the EGR valve located on my engine?
Thanks

CE still on???

Yes.

Go back in and get existing codes.

Key ON
Press DM Led button for 2 secs.....release.
Count flashes as they come back
Repeast until all codes have appeared. Write them down and then clear all codes.

To clear, hold button for 8 secs after each code appears.
Turn key Off for 50 secs , On for 10 secs and start car .. Codes will be clear and CE should be out.

Post findings

Don't have a code reader or manual yet so I'm relying solely on the code printout from the dealer at this point. Could you provide instruction on the location of the egr valve and temperature sending unit so I could perform a visual inspection of the vacuum hoses, wiring and general condition of these components?
Thanks,

94E

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Don't have a code reader or manual yet so I'm relying solely on the code printout from the dealer at this point.>>

Your car has a code retrieve set-up right under the hood.
A black box in front of the battery with a press button and LED light on it.

Do a search on Code Retrieve for procedure or follow the instructions I posted for you and post your findings

Cool, will do

I followed your instructions and the light blinked five times, then eight times. I have cleared the codes per your insruction and the check engine light is currently off; I will continue to monitor the light , and will repeat the process to retrieve codes should it come back on. While looking for the diagnostic module I found the egr valve and associated tubing which is a combination of aluminum, I think, and orange rubber. I'll have to remove the small section at the front of the valve cover, or utilize a telescoping mirror to examine the connnection of the organge tubing to the motor. The egr valve housing appears weathered but otherwise intact. I still have not located the temerature sending unit to visually inspect it. Thank you for your assitance thus far, it has been invaluable.

94E

As soon as the CE comes back, get the code .
The EGR is a known troublesome code on that chassis , However, it is easy to diagnose with a couple of simple flow test. If it comes back, post it and I will run you through the test procedures ..these will help you differentiate if it is a vac problem, EGR valve fault, or EGR tube blockage problem.

Well, I thought I was going to get away with it, but guess not. This afternoon when I started my car after work the CE light came on again after being un-lit and driven ~80 miles since Saturday. I pulled the code per your previous instruction and read back only one, 005; I've erased and re-set the light and it hasn't come back on yet, but I'm sure it will. What do you recommend? I want to thank you and this forum again for the wealth of invaluable information and, I've told my boss about this websight as he has a '78 or '79 Mercedes diesel he has had trouble with off and on, and he is excited about registering with the forum as well.
Thanks again,
94E
p.s. I don't know if it's relevent or just coincidence but, both times the light has come back on after being serviced from the dealer, and me erasing the codes, has been on the same day I've refueled it.

http://www.peachparts.com/shopforum/showthread.php?t=161017

Start reading at thread #39

Nope. As Arthur writes in the thread he referred you to, the code is there to stay until the problem causing it has been resolved. I am having the exact same code 005 issue with my car and have yet to do the vacuum test, but will tackle it when the weather cools off and dries up next weekend. I am, however, studying the EGR tube path, and connections, in case that needs to be replaced or cleaned. (It's reportedly a pain in the neck to remove it from the car.)

The only influence appears to be the number of times the EGR valve is "called" within a given time span. I am not exactly clear on how that system works, but the first time I reset the code the CEL came back the next day, after about 4 or 4 restart cycles. The second time I reset the code the CEL returned two days later, after about 8 or 9 restart cycles. I am assuming the computer allows a certain number of sequential EGR failures before sending a code to the diagnostic module, which is why we can drive a while without the CEL illuminating.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black