Hi, Craig. From my experience you want to minimize the amount of time you ride with the sensor light on. When that sensor comes on and stays, you are through the pad where the sensor fits and are also grinding on the sensor itself. Keep in mind that the sensor is rubbing into rotor and the sensor itself is not as hard as the pad so in no time you will have ground the sensor off completely will will release the wire to just flop around. If your light has come on and stays on, I would not drive too many miles with braking before changed. Of course, if you are driving on the interstate where no or practically no braking is involved, you could probably go an unlimited amount of miles, but when you do brake the sensor will be ground more than in city driving. If the light is flickering, you have just worn through the pad and are touching the sensor. I would recommend changing real soon to keep any possible damage down on the brake system. Of course, I would recommend changing sensors everytime with new pads because sensor are extremely cheap (less than $2 each and your front will take 4).