The downstream is a ##&&% considering where it is and on my 01 Grand Prix the thing sits about 6 inches from the ground your best bet would be to use a hammer break the bad sensor then socket it off I did it with my upstream last night also unhooking the exhaust helps a bunch with reaching the sensor I'm in the position to where I already wasted money on it but I feel it would be better to put a straight pipe on it and eliminate the sensor completely