I keep getting multiple (at least 3 of the same) codes on my obdII scanner. p0014, p0420, p0442. the car seams to run decent but mpg is not all that great for the mostly highway driving i do (18mpg). The fuel pressure regulator was just replaced, along with a new generic gas cap. I have also got a p0015 code to pop up once in a while. What could be the issue with his car? I have considered a bad O2 sensor or Cat.