I seem to have a problem with one of the oxygen sensors in my 2000 Focus. A OBDII scan of the two sensors while driving home shows radically different signals from the two. (The engine does seem to run a bit rough, come to think of it.) The #1 sensor signal (red) is very rough, as if it has a loose wire that is rattling with the engine vibration. Although I have never seen a "good" signal, the #2 sensor (blue) sure looks believable. Does anyone have experience with oxygen sensors?
(The posting with the data plot can be seen at alt.autos.ford.focus)
--Dave Harris Honolulu, Hawaii