I replaced the Top oxygen sensor, the one that the meter told me was bad and the light went out. My mechanic told me to drive for 150 miles to reset the codes and after 130 miles the light came back on. What gives? PS: it is a 1999 Kia Sephia.

I replaced the Top oxygen sensor, the one that the meter told me was bad and the light went out. My mechanic told me to drive for 150 miles to reset the codes and after 130 miles the light came back on. What gives? PS: it is a 1999 Kia Sephia.
What was the code that was stored?