The problem started when i ripped the wiring on one my o2 sensors. The check engine light came on. I drove the car for half a year before installing a new o2 sensor. After replacing it I reset the ecu and the check engine light still comes on. I did a diagnostic and its showing that "HO2 heat sensor low" on all four sensors (bank 1 and bank 2) and so on. What is the problem?