Q: oxygen sensor

Hi Destiny. Thanks for the follow-up question. A V6 engine has (4) total O2 sensors, Bank One sensor 1, Bank 2 sensor 1, Bank One sensor 2, Bank 2 sensor 2. Bank 1 and Bank 2 refer to different sides of a V-style engine (driver and passenger side). The Sensor #1’s are located on each side of the motor and directly on the exhaust manifold. These are often referred to as upstream. The #2 sensors are located near the catalytic converter or downstream. They all work together to relay data to the ECU to adjust the fuel and ignition system. Since you are getting bad fuel mileage, you should probably have a professional mechanic complete a car is getting worse fuel mileage inspection. This will allow them to determine which sensor (or sensors) are faulty, and if other issues, such as the electrical harness that is attached to the sensor is faulty as well. If you want to be proactive and replace all (4) of the sensors and electrical harnesses, this might resolve your issue.