Rear O2 Sensor (1K0 998 262 T)

The O2 sensor measures the amount of unburned fuel in the exhaust pipe to adjust fuel mapping for less emissions and better fuel economy. When malfunctioning, your MPG and performance can suffer. Replaced fairly easily, you can restore your performance and mileage quickly. Be sure to add anti-seize on the threads to prevent it from becoming a permanent part of the exhaust. Regularly scheduled maintenance as these tend to fail slowly.