I have a very nice 1999 C280 Sport with all stock suspension and brakes.

Recently the little wear indicator yellow light (kind of a circle with dashes around it) for break pad wear has been flickering on - and will stay on solid yellow if I press the pedal hard.

I checked the pads - the fronts are THICK (at least the outboard pads) and since the rears were less thick I replaced them.

But - the light is still on - the front pads are just far too massively thick for me to assume they are the source.... How does this warning system function? I'd like to confirm it isn't a poor indicator sensor or something before presuming to change these fat-boy front pads.

Help!