Does the Air Quality Sensor really work?

Today I drove past a cow, a skunk and a cigarette while paying close attention to the recirc button (left light green) and noticed it never went to the right side. In fact I don't think I've ever seen it work. Anyone know if the "F.AUC SENSOR" can be cleaned/adjusted/calibrated/tested? This is part no. 64 11 6 917 001 on the radiator shroud.