Hello All! I have a 99 Contour 2.5 V6. CEL came on, engine seems to be running normal. Brought the car to autozone. Diagnostics show that Bank 1 O2S is bad. Now I am trying to figure out which one this is referencing. From what I understand bank 1 is the left side of the engine (front of car?)but then I see 2 O2 sensors. I'm guessing the up and downstream.. How do I know which one needs replacing???
Thank You!
FEDFIREGUY
