1996 Toyota V6 Avalon OBD2 Code P0420 Troubleshooting Guide
I own a 1996 Toyota Avalon with a V6 engine, and I'm currently experiencing the P0420 diagnostic trouble code. I recently replaced the downstream oxygen sensor after the catalytic converter, and after resetting the system, the check engine light returned. The code persists despite the replacement. What should I do next? This is a common issue on older 1996 V6 Avalon models with catalytic converter-related emissions problems.
Given the age of your 1996 Toyota Avalon, it's likely that the catalytic converter itself has degraded and needs replacement. A failing cat can cause a P0420 code even after replacing the oxygen sensor.