Where are the oxygen scensors located on a 98 ford expedition?

There are two of them and they screw into the exaust pipe, one on each side before the catalytic converter. Sometimes you can find them screwed into the exaust manfold as well.

Good luck!

The o2 sensors are loacated on exhaust pipes, they are screwed in, theres one on each side before the converter and one on eachside after the converter.