Toyota Repair: Tacoma Code P0420, otc scanner, threshold bank

Question
I have a 2000 Tacoma with 79,600 miles. It has a V6 with an automatic transmission. The truck runs fine despite the check engine light on. I have run through the diagnostics with my OTC scanner. Error P0420, Cat efficiency below threshold (bank 1) is the result. If I clear the code, within 75 miles the same code comes back. If I have an issue with the convertor, how would I know or test? Is it covered under warranty? Last, could it be the O2 sensor after the convertor? The specs at the O2 check out ok.

Thanks for the advice.

Answer
This is not an uncommon problem, there have been some problems with the cat converters,the cat converter can be tested by checking the waveforms of the front and rear O2 sensors, most importantly the rear sensor, it should have a pretty much steady voltage about .2-.3volts and very little fluctuation at about 2000 rpm with the engine warmed up, if the voltage fluctuates or there is a waveform that follows the front sensor it means the cat is not working and needs to be replaced, the warranty period for the converter is 8yrs/80,000 miles under the federal emission control warranty, it may be a good idea to contact the toyota dealer before the warranty runs out.