P0420 code on 2005 Elantra. The CEL is Off.

nickv41

My CEL came on a few weeks ago. I did not own a scan tool so I ordered one. By the time it arrived, the CEL light turned off. Great news. I plugged in the scan tool not expecting to find any codes but I did get a code P0420 "emission system not operating to full efficiency."
Since the CEL light is not on, I'm wondering if I should just erase the code or leave it alone. If I leave it alone will the car pass inspection if the CEL is off?

Karen_S

http://lifehacker.com/5878754/the-five-most-common-check-engine-problems-and-what-you-should-do-about-them