Brake Mileage
Not sure if brakes ever done, bought used at 25k as a certified car.
Sensor light came on.
Dealer is stating brakes only last 12-15k miles

Is that a for real number?

Seems lousy for a car driven very easy by the wife.

I'd check breaks manually (I think the sensor is on front passenger side) - take tire off and check breaks; if OK, replace break sensor. Before you do entire operation buy break sensor and replace it anyway if you have any doubt.
I got similar problem (when I did full right turn, it kicked my break light). MB replaced entire harness as part of warranty coverage.
Maybe the previous owner was a two-footed driver?



