[Morley]

The black carboning won't cause problems. Its when they get the white powder on them that causes problems, silicone poisioning. If you have O2 sensor related codes you need to first find out what is causing the codes, weather it be the sensors themselves, stuck injectors, bad gas, plugged fuel filter, or air filter, etc. Only after finding the exact problem and fixing it should you replace the sensors, otherwise you could end up ruining them too.