I just owned my car for about 7mths, it's a C180 (yr 94) with AMG facelift. I have been reading about MB's problematic areas, which most of the time, is the AIR MASS METER. But, what is it exactly ? Is that for the airbag ? How do we take care of it ? Also my car is reaching 100k miles, when it the time I will be required to change the timing chain ?