Hello Sir or Madam. Welcome to justanswer!
You need to have the adaptation values cleared out of the computer. This cant be done with a regular scan tool. It has to be done with an MB specific tool. The dealer charges a half hour to do this. The codes will return with a new sensor or not until you get the values cleared.
Ok, if you're at + or minus 10 percent or less your good. Some techs don't reset the adaptation I however do and have been doing so since these airflow sensors started failing at 50K miles often. I have had at my dealership at the time had 5 comebacks from not resetting the values. Once that was done I never had a light again after doing the sensor. Have the values reset. By the book thats the right way.