'95 E420, Code 6, shes sick.
 

1995 E420 with 144K on the clock.

code 6 is comming up which I beleive means something is up with the idle speed control....no? which makes sense taking into consideration the following symptom. there has been recent episodes where, during idle, the engine is, for lack of a bettter word, surging. rpms rise (though not past 1000 if i'm correct) and then plummet. the car "catches" these drops and I guess is trying to correct it. this results in the car almost, but not actaully stalling out. due to the rpm shift the engine and exhaust noise rises and falls to a deep, bassy shudder.

what do i have to replace?

There is no longer a part called the idle speed controller. It's done by committee. A code 6 on the DM is telling you to check pin 7 for more codes. Next step should be to check the codes on the other pins on the 38 pin diagnostic connector.

I get codes via the LED. Is there another way to get more/different codes?

The further clarify the symptom, the car surges between 1000 and 1500 RPM while idling in P. There is no problem while in gear (driving around, or sitting at a stop light for example).

The LED will not give you all the codes. You need to build a "home-brew" tester, or buy a tester. Go to the bottom of the page in this link. http://pages.prodigy.net/jforgione/MB_X11.html

I recently had code 6 on my 94 E320, and the Throttle Actuator made a grinding noise with the engine off and the key in the "run" position. A rebuilt TA from 4.Mercedes.com and everything is right again. If in addition to your other issues, your cruise control is not working, then it is a good bet your TA needs replacing.
Mark

theres a mention of the system being analog or digital. Everything up to 1993 is analog, it said 94's were mixed, but what about 1995's?

Good question.

No comprende 4993. I think Jim was referring to the built in LED on the 140 body. 124s all have flash code reading on either the 16 pin or 38 pin connector through 1995. The 16s have a built in LED and all the 38 pins I've seen have an ancillary 8 pin connector with an LED. But even if there's no LED you can read the DM codes on main connector.

1) Has the wiring harness been replaced?? Check it out near the connector to the MAF. . open the shield and see how the wires look. If it has been replaced, no need to do this check.

2) could be the ETA . . checkout MENU#24 for a typical scenario and the codes that show up in the various ECUs. It also could be just a 'brake switch' or Neutral Safety switch; much cheaper if it is.