P0411 — Secondary Air Injection System Incorrect Flow
Low severityWhat it means
P0411 is stored when the engine control unit sees a fault involving the secondary air injection system. The secondary air injection system pumps fresh air into the exhaust after a cold start to help the catalytic converter heat up and cut emissions. The control unit measured a flow that does not match what it commanded, so the system is not moving air or vapour as expected.
Common symptoms
- Check engine light with no strong driveability change
- Usually only a check engine light
- A possible failed emissions test
- Rarely any driveability change
Likely causes
- Blocked passage, stuck valve or solenoid
- Cracked or disconnected hose
- Faulty secondary air pump
- Stuck or blocked air-switching valve, or its hoses
What to check first
- Inspect the related hoses, valve and solenoid for blockage or leaks
- Listen for the air pump running briefly on a cold start
- Inspect the valve, hoses and connectors
Can you keep driving?
Safe to drive; it mainly affects cold-start emissions, so repair to pass inspection.
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All information, explanations and guidance on this page are general preliminary information only. They are estimates and may be entirely wrong, incomplete or inaccurate, or may not apply to your vehicle at all. Never take any action based on this content alone — do not decide to keep driving, clear codes, replace parts, repair or otherwise work on your vehicle based only on what you read here. In every case, and for any final decision, you must consult qualified technical personnel (a professional mechanic, an authorized service centre or an engineer) and obtain their approval before acting. MechanicAI accepts no liability or responsibility whatsoever for any damage, fault, injury, loss or outcome that may arise — directly or indirectly — from using or relying on this information, for any reason and under any circumstances. By using this page you acknowledge and accept these terms.