I have both "upstream and downstream"-(Haynes manual) that are bad. I replaced my knock sensor this past weekend since it was one of the things gone bad, but I was just curious if I should care to replace the 02 sensors. I don't have to mess with emmisions inspections where I live, so if thats what it would involve I guess I shouldn't worry huh?

 

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The KS was probably bad because the O2s are bad. Always replace the O2 sensors before the KS. Replace them as they cause bad gas milage, may cause you to run lean/rich, one of those.