After 2 1/2 years of ownership my i30 finally had its first mechanical problem. A few days ago, I got a CEL! I ran a self test on the ECU and got codes 0304 (knock sensor) and 0115 (fuel injection system running lean). I wonder if this could be a case of one thing causing the other?? I used my multimeter on the KS sub-harness and there was continuity (about 4.5 Mohms) there. I don't even know where to start with the fuel injection system, it could be so many things (injectors, intake leak, oxygen sensor, MAF sensor, fuel pressure)!! I replaced the fuel filter not but 5k ago and used a can of quality injector cleaner last fall and the car still runs smooth and fine. You guys got any ideas??

 

i think i got those same codes when i forgot to hook my MAF back up when i was messing around with my intake. i however did get a MAF code too along with those.