I don't know the codes off the top of my head but the reader said they should be replaced in pairs. Any o2's you get from canadian tire will not be oem there for not have built in heaters which I understand is almost a MUST for contours to function properly. I am not trying to act like I know all about this car but I did get this info right from a good mechanic who I have been frineds with for 9 years.
