Toyota Highlander
P0421
The P0421 code on a 2020-present Toyota Highlander indicates that the engine control module (ECM) has detected a warm-up catalytic converter efficiency issue, which may lead to poor emissions performance.
2 SolutionsP-CodePowertrain
P
Error Code Type
Powertrain
Components
1 affected
Exhaust System
Symptoms
7 common
- •Check engine light illuminated
- •Decreased fuel efficiency
- •Rough engine idle
- +4 more
Most Affected Generations
1 generation
XU70
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
7
Common Symptoms
1
Generations
All Solutions
Showing 2 of 2 solutions for error code P0421 across all generations.
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