Hyundai: 1996 Hyundai Elantra code

The converter is probably bad. Check both oxygen sensors to be sure
they're operating properly. If so, you'll need a converter. I've only
seen this code once where the vehicle didn't need a cat, and that was on a
Sedona where the engine had been replaced and the mechanic apparently was
colorblind; he swapped the front and rear oxygen sensor connectors. I
don't think that's a possibility on your vehicle, however.

Any chance you're still within the 8/80 emissions warranty??