jlofthouse

My check engine light came on and I checked it and these two codes came up. I started with replacing the back oxygen sensor, but the two codes are still on. I usually use Chevron gas. I feel like it burns oil quickly, so oil could be moving past the piton rings. It also seems like there is a lower fuel economy. Any advice? What could it be, and where should I start with problem solving? Someone I talked to said it could be the Catalytic Converter, could this be true or likely not?