Help Check Engine Light

I have a 2001 accent that has the infamous check engine light on. I went to Autozone and their reader gave the codes: P0138 "O2 sensor bank1 sensor 2 high volts" and P0141 O2 sensor heater sensor failure". The vehicle does not appear to be running rough or abnormally at all and the fuel economy hasn't changed. I cleared the message by pulling the negative battery terminal for a while but after a few minutes of driving the light came back on. The light came on again after Autozone cleared it with their reader.

I used to have a '96 accent and I know that it had 2 02 sensors. I just recently purchased this 2001 accent and don't know anything about the emissions control system. I'd get the Haynes manual but those things are sometimes more confusing than helpful.

Just wondering if anyone has seen these diagnostic codes before and if so which O2 sensor is the culprit? I'd go with the shotgun approach but these things typically are not cheap.

I GUESS THE BIG QUESTION I HAVE IS ARE THERE MORE THAN ONE 02 SENSORS ON A 2001 ACCENT AND IF SO HOW DO I DETERMINE WHICH ONE TO CHANGE?

Any help would be greatly appreciated.

Sensor 2 is the lower sensor, in the exhaust pipe. Parts # 39210-22620. List price is $87.32. Give me a call and I'll sell to you for $75 shipped.