The heater element in a OBD 2 or 4-wire O2 sensor is used for nothing more than to get it a little bit hotter so the computer can acheive closed loop operation faster. PO135's are extremely common, as the heater elements frequently short internally. I would not recommend disconnecting the battery to clear DTC's. OBD 2 cars very sensitive to having adaptive strategy wiped out from the PCM. These cars also hardly ever set a false code, if it set there is a 99% chance there is a definate failure. It may be as simple as a PCM reflash, but still a failure.
If your knowledge of the car is limited your best bet would be taking to a technician you can trust. It is still under warranty after all, so rather than screw with it yourself, go get it fixed for free.