Well just a couple of weeks ago I've put new performance cat cam cam shafts in my 99 Hyundai Tiburon FX (I know this isn't a Hyundai forum but i cant seem to find help elsewhere). When I first started my car after i installed my cam shafts I had no CEL and no problems. Then i shut it off and a while later I took it for a spin and i saw my check engine light was on. I hooked my computer up to it and I was getting a code p0343 camshaft position sensor high input. I don't know what the problem is with that and why my CEL would turn on. The car runs great with the cams. Maybe need a new sensor for the cams or ?