A P0420 diagnostic code on your 2021 Honda HR-V indicates that the catalytic converter efficiency has fallen below acceptable thresholds. The first-generation HR-V (2016-2022) uses a 1.8L 4-cylinder engine with a single exhaust bank.
2021 HR-V Engine
The 2021 HR-V uses a 1.8L naturally aspirated 4-cylinder engine producing 141 horsepower. This engine uses a single exhaust path with one catalytic converter, so there's only Bank 1 to consider.
Common Causes
- Converter Aging: Normal wear over time
- O2 Sensor Issues: Faulty upstream or downstream sensors
- Exhaust Leaks: Air entering affecting readings
- Engine Misfires: Unburned fuel damaging converter
- Oil Consumption: Oil contaminating converter
- Fuel Quality: Poor fuel degrading converter