I have a '95 Altima. Six months ago I replaced the front O2 sensor after getting codes for O2 and Knocks. Zeroed out the codes and all was well--didn't need to do the Knocks sensor as the O2 was causing it to code. Now the same codes are back and AutoZone tells me it may be the rear sensor. They only list one O2 sensor.
Are the front and rear sensors the same? Any advice appreciated.
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-Doug