So today guys after finishing my motor mount....I got CEL codes 12,21, and 55....keep in mind my TJ is a 97......code 21 is for the 02 sensor...I have replaced the 02 sensor with an AC/Delco one from rockauto.....it's brand new....yet I get the upstream 02 sensor code 21 again.....should I buy dielectric grease and ensure the connection?....I have checked connections and this sensor is brand spanking new....what gives?