Can anybody tell me if this sensor has any control on my engines Air/Fuel/ Engine Parameters ? I had a service engine light come on and the dealer told me I have a rich condition in bank 1 and bank 2. He also said I may or may not need an 02 Sensor. I have 2 upstream and 2 downstream. If both bank 1 and bank 2 are running rich would that be the upstream 02 sensors ? And do these sensors tend to go bad at the same time ? What do yall thin about this ? Thank you for help .