Well, I guess I spoke out of place here, not knowing if the later MB cars used a MAF sensor or not. I had assumed that the later models might, and thought that this info might be of use.
MAF, mass air flow sensor, on my VW anyway, measures the amount of air going into the engine. This is how VW's ECU knows that the EGR is working, by watching the intake air flow. The ECU is adjusting the airflow to the amount required for engine load and RPM, to keep NOX emission down. If the computer can't adjust the flow to the amount that it computes the engine needs, it will 'throw a code' and illuminate a check engine light.
This is a great forum board, full of information, but it is keeping me up late night reading
For now, I will go back to reading and learning!