Reset check engine light on 2001 SLK 320 - 2000 Mercedes-Benz SLK

SOURCE: reset service indicator light

from what i can gather
turn ignition on and press the button to the left of the speedometer 2 times and then turn ignition off

SOURCE: How to reset 1999 E 320 check engine light

Make sure you are using premium gasoline and have the car scanned (OBD2) most likely you will need to replace O2 sensor.

SOURCE: I have a 2002 Mercedes Benz SLK 320 w/about 87K

By having it scanned and cleared with an OBD tool. This light comes on when it detects a problem. Could be a bad gas cap, or it could be a misfiring engine. The code you get from having it scanned will pinpoint the trouble area

SOURCE: when I press the power door lock switch on my 2001

Looks like the trunk lock has a problem and not locking with the rest , as the rear lock ia a master lock. You need to check it and replace if necessary.

SOURCE: does the 2001 mercedes slk 320 have a fresh air

Most likely if you have one it will be behind glove box.
You'll have to remove glove box and you'll see it.
Another way to check if you have ACC CABIN filter is to go to parts store and ask them to check by application.
Hope it helps.