GM-GMC: P0300, mechanic, scanner

Question
Did a complete tune up, cleaned the injecters, etc After about 500 miles the light came back on. Everything runs great but my mechanic cant figure out why the light keeps coming back on. Any Ideas Thanks Brian

Answer
Without knowing what you are driving I can only tell you that a P0300 is a misfire related code and if the vehicle is new enough a good scanner can display what cylinder or cylinders have or are misfiring and can narrow your search to the problem cylinders.
Hope this helps