I have already replaced both 02 sensors upstream on bank 1 because the code is P0135 (02 snsr heater circuit malfunction bank 1 snsr 1). I also cleaned all connectors. After replacing both sensors and reset the light, it came back on and say's the same fault code. I can clear the code, run the car as long as I want and the light stays off: until you shut the car off and turn it back on. Then the engine light comes on right away. What now????