I am new to this site, but I have found many useful posts on here. I appreciate all the good info. Here's a good stumper for the group on my 94 E420...It has recently developed a high idle issue (@1100rpms) in park. There were no warning lights on the dash, but I decided to pull codes anyway to see what was going on. Code 6 was displayed on my Baum scanner which says "idle speed incorrect; fault from EA/CC/ISC". After some trouble shooting, I decided to replace the throttle actuator, brake light switch, and neutral safety switch. The car still has the high idle and the car always has that code return if when I clear it. All parts are from the dealer and brand new. Vehicle temp. does not seem to make a difference. Any thoughts?

Probably a vacuum leak allowing it to increase the idle. Check all tubing and rubber bits under the hood.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I forgot to mention that I have checked and replaced all weak rubber and vacuum line connections as well as replacing the engine harness. I am totalling stumped. Also, when you apply the gas pedal and then release it the rpms will flucuate between 1000 and 1200.

Could be idle control valve opening too much, or a temperature sensor.....I usually throw parts at problems though.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)