Just finished doing brake job, had some damaged calipers that had to be replaced because I trusted sensor too much. It never made noise, never triggered warning.

Over years guides got crusted too much, so front brake pads weren't traveling symmetrical on both sides of the disk, as a result sensor never got triggered while one of the pads got worn down all the way to the metal. When I noticed groove in the disk it was too late - so new front pads, disks and calipers (needed only one but decided to do them all).

Moral of the story - check your brakes regularly, sensor can lie.