Car News Take 3

So my car guy finally called me and gave me good news... Sort of... He drove my car again this morning and could not hear the backfiring... So he is going to fix the oxygen sensor (which is why my check engine light is on) and hope that does the trick. He looked at my car several times and said the engine looks good and he cannot figure out what the problem is if there is another one. So I am going to pray that the oxygen sensor somehow miraculously fixes the backfiring sounds and that my car works normally when I get it back. If it keeps backfiring, he said to bring it back and he will go out with me to drive it and see if he can figure out the problem. But either way I am happy that I get my car back tomorrow morning and the repairs did not bankrupt me!!!