Do a search if this doesn't work. This is off a 98 E430 (thanks bill!). There is other info in the search that might help.
Make sure your doors are closed.
1) Insert key into ignition and turn to position 2.
2) Within 4 seconds push button "0" and release.(this is the odometer reset button)
3) Within 10 seconds turn key to position 0.
4) Press and hold button "0" while turning the key back to position 2. Continue to hold button "0".
5) After approx 10 seconds a signal sounds and the display will show 10000 miles or 15000 km. Release the button.
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03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
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1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)