my check engine light came on a few weeks ago. i took it in and had a code scan. it said that the o2 sensor in my ehaust manifold was broken. since i didn't know if it was the left or right bank i replaced both. after i drove it a few miles the light came back on. so i took it back and had the code scan ran again. and it still said that my o2 sensor was broken. is there a fuse that may have burnt out that would cause this reading or maybe even a wiring problem?