where are the "rear O2 sensors located. on 2003 Ford Expedition

I can only find the ones forward of the exhaust Y. Those were replaced recently.

by in Irving, TX on July 13, 2012
2 answers
ANSWER by on July 13, 2012
Behind the catalytic converter.
ANSWER by on July 14, 2012
you should have 2 in frt of catt at y and 2 behind those on the upper side of the exh pipe,some are hard to see