2000 Toyota Sienna P0420 Fault: O2 Sensor or Catalytic Converter? Diagnosis and Warranty Info

Model: Toyota Sienna Fault Code: P0420 Posted: 2009-09-20 08:49

I own a 2000 Toyota Sienna with 72-000 miles on the odometer. The check engine light has activated, and the diagnostic code displayed is P0420. Online resources are inconsistent—some point to a faulty oxygen (O2) sensor, while others suggest a failing catalytic converter. I'm looking for clarity on how to determine the root cause. Is there any warranty coverage available for the exhaust system on this model? Any advice or troubleshooting steps would be greatly appreciated.