Ive had a problem with my 2000 S10 4.3 with the Bank 1 upstream O2 Sensor failing. I replaced it twice with the first one lasting about 350 miles. Idont know If the sensor was at fault or I have another Issue. My scan tool is showing on the st and Lt of over 10% on the Bank One sensor. The codes was also showing the 02 sensor fault and 0171 . I cant find any vacum leaks and Fuel pressure is within range. Both times I replaced the sensor the It was black. i dont have any flow charts for this, if any body can Help it would be App.