Is there an additive to help clear O2 Sensor?

I have a 2005 Pontiac Grand Prix GTP that had the engine light come on. I went to a mechanic and he said I need to replace my oxygen sensor, which he said will cost about $300.. I was wondering if there was an additive to put in my fuel or something that will clear the o2 sensor so I don't have to get it replaced or do I have to get it fixed? Thank you for your help!