Hi there I have a 2011 chevy cruze that is throwing p0137( o2 sensor circuit low) p2270 (sensor lean bank 1 sensor 2) I have replace the o2 sensor, valve cover, intake manifold all with oem parts and the codes will not go away. I've also had it smoked and there are no leaks. I've had 3 different people look at it an no one can figure it out. Any help would be greatly appreciated