I am sorry, I forgot to finish the sentence regarding where to pour the vinegar, how embarrassing! Yes, pour the vinegar in the bottom of the tub and allow it to sit overnight. That sensor is in the sump assembly, mounted near the bottom. The mineral deposits block the little eye used to sense the particles. The vinegar will help to break the minerals up and clean off the eye so it can see well again. Try the vinegar and let me know what happens.