I'm getting a lean code P2270 on Bank 1 sensor 2 after x pipe install and according to the scan tool at work that sensor is reading 0.00v while the other 3 have atleast .500v after warm up . B1S2 will read .05 for a split second then go back to zero , but thats it. I swapped both rear sensors for each other but I still have zero volts on B1S2 ? Wiring issue ????