My Stepson's 2000 Taco just threw the same code yesterday. According to the service manual, the most likely cause is a bad O2 sensor in front of the converter. I checked his out with and ohm meter, and sure enough, the sensor read way out of tolerance. The stealer quoted him about $120.00, I think -- said they'd have to order it. I checked AutoZone and NAPA online, and both were more expensive. Good luck.