Hi, I have a 2015 Mo and CEL code of P0037 & P0138. Those are calling attention to a bank 1 sensor 2 issue. Took the quick route and replaced it myself. No luck. Took it to Nissan and they said (originally) that it is bank 1 sensor 1 causing sensor 2 to read the error. Didn't quite believe it but okay so changed that one myself after paying their diagnostic fee. Nope not the problem codes came back. Brought to Nissan again and I said just fix it! They now said it is bank 1 sensor 2 (the original one I replaced). After pulling down the exhaust system they said the sensor (only 2 weeks installed) is rusted on and I need to replace the CAT and the sensor since they can't get it out ($3,000+). Told them put it back together ($550 for that work) and still no fix. Any help? Seems to me the problem is not the sensor but something causing the sensor to read that error. Any advice is much appreciated, money is tough and I'm handy but have no idea what to look at next and can't pay these people $3,000+ on top of what I have paid already. Thank you all so much!