Catalyst System Efficiency Below Threshold (Bank 1)

What does this mean?

Code P0420 indicates the catalytic converter on Bank 1 is not operating at maximum efficiency. The PCM monitors converter efficiency by comparing the upstream and downstream oxygen sensor signals. When the downstream sensor mimics the upstream sensor's switching pattern, it means the catalyst is no longer cleaning exhaust gases effectively.

Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Tesla Model-3 models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.