2010 Xterra 156,550 miles on it. I had to replace the Bank 1 Sensor 1 02 sensor. The cel is still after put in the new 02 sensor. So I ran a scan it showed P0171. I haven't drove but around 15 miles to see if the gas mileage went up. It was 8 mpg, now 21 mpg with the new sensor. I don't know what the P0171 is for and how to get the cel off