A P0420 diagnostic code on your 2020 Honda Odyssey indicates that Bank 1's catalytic converter efficiency has fallen below acceptable thresholds. The Odyssey's 3.5L V6 uses a dual-bank exhaust system with separate converters for each bank.
2020 Odyssey Exhaust System
The 2020 Odyssey uses Honda's 3.5L V6 with a dual exhaust configuration. P0420 specifically affects Bank 1 (the rear cylinder bank near the firewall). Bank 2 issues would trigger P0430 instead.
Common Causes
- Converter Aging: Normal efficiency loss over time
- O2 Sensor Failure: Bank 1 sensors malfunctioning
- Exhaust Leaks: Leaks on Bank 1 exhaust path
- Engine Misfires: Bank 1 cylinder misfires damaging converter
- Oil Consumption: Oil contaminating the converter
- VCM System Issues: Variable Cylinder Management affecting Bank 1