The oxygen sensor has 0 voltage, and the code is indicating HO2S (Heated Oxygen Sensor). O2 sensor is not working. That is why fuel system is not optimim at the moment, this condition is called overfuelling and the exhaust silencer has black smoke because of excessive unburnt fuel.
Before replacing oxygen sensor, you can check the existing sensor for following:
1) Make sure it's connector is not corroded, if it is, then clean it with degreaser (perform this service only after taking off sensor when engine is cold)
2) Make sure it's terminals are not loose.
Make sure that wiring is not burn on exhaust components.
3) Holes in exhaust getting unmetered oxygen into exhaust system.
4) Make sure there are no vacuum leak at the engine.
If this problem doesn't get solved after taking above mentioned measures, then it is a faulty O2 sensor. Replace it.