My service engine soon light came on so I plugged in my OBDII scanner and it said: PO171 bank 1 system too lean PO174 bank 2 system too lean and PO 300 random-multiple misfire detected...the car runs just fine. Is this a serious problem or can I reset codes and see if it comes up again? I drove it for an hour or two after the light came on and it ran just fine. Is there somewhere I can find out exactly what those codes mean?