Thanks. I believe it said bank 1. Once the sensor is changed, does anything have to be done to reset the check engine light or will it go out by itself?
That will depend on why the code was set. Diagnostic codes don't ofter specify which part is bad, but rather what sensor is reporting an issue. Depending on the particular diagnostic code (there are SEVERAL relating to oxygen sensors), the issue could be with the wiring, due to a misfire/vacuum leak, improper fuel, etc. If you just replace the sensor and the problem is a broken wire to the sensor, no, the check engine light will not go out.
Do you happen to have the exact code, probably in the form of P0123?