I understand that the 1998 Explorer Sport has 3 Oxygen Sensors. I am wondering about the location of each of them. I can only find one which is very near the front driver side wheel.

 

On my 98 Explorer with the 4.o SOHC has 4 oxygen sensors. One before the cat. and one after the cat. on each side.

 

There are three sensors on the 4.0L OHV, one on each side right behind the exhaust manifold and one behind the cat. I found it easy to remove the inner fenderwell to get to the 2 behind the manifold. the one behind the cat is easy to see and not too difficult to get to either. All three sensors are on the top of the exhaust and point upward. If it is the 4.0L SOHC it does have 4 sensors like Bulldog posted.