My wife's 190e had the dreaded ABS light come on and stay on about two weeks ago.

OVP relay was fine. Mixture in close loop with fluctuating duty cycle. Idling fine.....well normal for her car.

Front speed sensors replaced within the past two years. Which leads me to either a problem with one of the newer front sensors or the original rear sensor.

I will check all, but I am curious.

Tinker