The "Check brake pad wear" message on your Mercedes simply means its brake pad material has worn down to the minimum thickness. Besides, this message may also appear due to a faulty sensor. Under no circumstances should you ever ignore such messages.
9. An error message like this can appear
due to one or more of the following
reasons:-
When the brake pad material is at its
minimum thickness.
If the sensor responsible for measuring the
brake pad thickness goes bad.
If there is something wrong with its circuit.
10. In any case, it's not safe
to drive a Mercedes that
displays "Check brake
pad wear".
11. Why so, you asked? Go through
the below discussion.