Originally Posted by professor

I have done these adjustments on my 1988 190E last week and my 1989 560SEL a couple of years ago without the knowledge of a "diagnostics mode". Such a mode might be true on newer cars but I never had to deal with that on my old clunkers.
The 560 has passed emissions and has been the most reliable car ever at over 300K miles.
What is your car model and year (maybe I should read the first thread )