Past few months I always have the CEL come on and off with the code P0174 which leads too bank 2 o2 sensor running lean. The car always seem like it lost power and doesn't run like it use to be. So i decided to install my HFPC this past weekend. When I pulled out the rear pre cat, I found out that the bottom o2 sensor was really loose and there was white stain on the sensor when i pull them out. This might be one of the problem for some of you guys that have the same code. So just check the o2 sensor next time when the code pops up