Good morning,

We had a field engineer tell us that the MAF sensor failures were caused
by impact damage to the sensing wire by sand or dirt. Most of these cars
had an air filter that had shrunk and caved in or wasn't sealing anymore.
When you take the sensor apart, you could see little dings and nicks on the
sensing wire with a magnifing glass. The sensor cards looked sandblasted.
MB updated the airfilters around 2000/01 with a center support rib built into
the filter to help keep their shape, but they still do it.
Over oiling K&N style filters can spell instant death for MAF sensors. The oil gets pulled out of the filter right onto the air mass.
Sometimes cleaning them with electronic parts cleaner can bring them back.

I would recommend inspecting your airfilter and housing yearly to make sure there is a complete seal on all 4 sides of the filter. Any leaking dirt should be
fairly obvious to see on the filter gasket. Check the air boxes too, some of them have been warping and not sealing due to engine heat.
Turbo diesels 98+ and AMG's can be pretty susecptable to this.

I have replaced several engines due to unfiltered leak air wearing down the cylinder walls and for some reason, these cars had several MAF's and no one ever caught on to the slow engine death being done.

Have a good day.
Dr.D