high idle
 

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.

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. :D