93 del sol Check engine light

OK, i did the jump and got a code for the oxygen sensor. Now in my understanding, there is a pre-cat and a post-cat sensor. Which one is it?
EDIT: It's Code 1

The O2 is located before the cat. Check for voltage between terminals A and B (top two terminals comming from the sensor.) The sensor should produce .1v when the engine is cold and fluctuate between .1 and .9 when the engine is at operating temp. If the sensor doesn't do this, replace it.