Hyundai Repair: emissions - failed smog, fuel octane, engine temperature

Question
I have a 00 accent that fails smog because of high nox.  The check engine light is not on and nothing shows up on the diagnostic machine.  What or where should we start to fix this so that it passes smog.

Answer
You should check the make sure the thermostat operates normally and that the fuel octane is 87 or higher (usually the lowest grade available at the station, so I doubt this is the issue).  If your engine temperature isn't too high and the fuel is 87 octane or more, I'd expect you probably have a catalytic converter issue.