Code
P0411
Emissions
Secondary air injection system incorrect flow
The secondary air injection is not delivering the expected airflow.
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Most likely causes
- Failed air pump
- Leaking check valve
- Blocked air passages
Symptoms you may notice
- Check engine light
- Failed emissions test
Checks to run
- Verify the air pump runs at cold start
- Inspect check valves
- Check the fuses
Tools you may need
Multimeter
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.
Related codes in Emissions
P0420