Honda Repair Questions? Ask a Mechanic for Answers ASAP
Ok. The P0301 is a misfire on cylinder #1. The P0135 is a code for an oxygen sensor. More than likely, the misfire on #1 cylinder is making the oxygen sensor set a code due to the unburnt fuel from cylinder 1 getting into the oxygen sensor and messing it up. I do believe that if you cure the misfire the oxygen sensor will clear itself out, and go back to normal. The misfire (P0301) is more than likely going to be a bad ignition coil. It is located on the passenger side, first coil closest to the front of the vehicle. You will also want to check the plug on this cylinder as well.