Honda Civic
P0421
The P0421 code indicates that the engine control module (ECM) has detected a problem with the warm-up catalytic converter efficiency in the Honda Civic 10th Generation (2016-2021).
2 SolutionsP-CodePowertrain
P
Error Code Type
Powertrain
Components
1 affected
Exhaust System
Symptoms
8 common
- •Check engine light illuminated
- •Decreased fuel efficiency
- •Poor engine performance
- +5 more
Most Affected Generations
2 generations
FL
1
FC/FK
1
Top Affected Components
1 component
Exhaust System
2
Severity Levels
1 level
medium
2
Quick Facts
2
Total Solutions
1
Affected Components
8
Common Symptoms
2
Generations
All Solutions
Showing 2 of 2 solutions for error code P0421 across all generations.