The Emissions Act of 1992 mandated that "ANY" repair shop should be able to SCAN & retrieve info on emission problems. Starting in 1996 ALL cars sold here have a universal ODB2 connector that a scan tool can be connected.
STORED codes are what almost always turn the check engine lamp on! Rarely do you have "active" codes.
You are correct as far the air mass being the problem. We replace 10 or more them every week.
On the C230 the part number is 000-094-09-48, list is $442.
Takes about 10 minutes to install & is a DIYer.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)