Ford Explorer
P0421
The P0421 code indicates "Warm Up Catalyst Efficiency Below Threshold (Bank 1)" in a 2011-2019 Ford Explorer. This typically points to issues with the catalytic converter or related components.
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 or sluggish acceleration
- +5 more
Most Affected Generations
1 generation
U502
2
Top Affected Components
1 component
Exhaust System
2
Severity Levels
2 levels
medium
1
high
1
Quick Facts
2
Total Solutions
1
Affected Components
8
Common Symptoms
1
Generations
All Solutions
Showing 2 of 2 solutions for error code P0421 across all generations.