P0411 Code: Secondary Air Injection System Incorrect Flow Detected
🟠 Moderate severity · drivable
Drivable — this affects cold-start emissions, not drivability. Fix it before your next emissions test.
What P0411 means
The secondary air injection system isn't flowing the right amount of air into the exhaust during cold start — either too little or too much.
Symptoms
- Check engine light is on
- Possible failed emissions test
- No driving symptoms
Common causes
- most common: Faulty check valve or leaking hose
- common: Faulty secondary air pump
- less common: Clogged air injection passages
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace leaking hoses or faulty check valves | Yes | $50–150 |
| Replace the secondary air pump | Mechanic | $200–500 |
Frequently asked questions
Can I drive with a P0411 code?
Yes. It only affects cold-start emissions, not drivability.
What is the most common cause of P0411?
A faulty check valve or leaking hose, or a weak secondary air pump.
How much does it cost to fix a P0411?
$50–$150 for valves and hoses, or $200–$500 for an air pump.
Related codes
P0410
P0410 Code: Secondary Air Injection System Malfunction
P0412P0412 Code: Secondary Air Injection (AIR) Switching Valve A Circuit Malfunction
P0418P0418 Code: Secondary Air Injection System Relay A Circuit Malfunction
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.