getting trouble code P0155 bad oxygen sensor heater. how can this be repaired

It is your Bank 2 Sensor 1 Heater circuit in the exhaust. Unplug the O2 sensor on bank 2 (the opposite side of the the engine from cylinder 1) sensor 1 (before the catalytic converter). Looking at the O2 sensor plug, there will be usually 4 wires on a heated O2. Find the two wires that are the same color. That is your heater circuit in the O2. Using an multimeter, check the ohms through those two wires. It should be 3-5 ohms typically. If it is "infinite", "overload", higher than 20 ohms or 0 ohms, replace the O2 sensor. If you measure 3-5 ohms, you may have a wiring problem that will need to be investigated further with a wiring diagram.