The problem all started last week, i went to start my car and it wouldnt start & the engine light was coming on so i had a look and thot it might of been the plugs getting wet as one was rusty and i dont have a top mount now so thought water was getting in the vent. I got new plugs and fitted them, the problem went away well so i thought went for a drive everything was ok until i booted it then the engine light came on again and it started popn & banging. When i got home i tested what codes were making the engine light come on and its telling me codes 31 & 34. Can any one help me out with what could be causing this.