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P0411: Secondary Air Injection System Incorrect Flow Detected
Severity: Low Usually safe to keep driving, but get it checked.
What does P0411 mean?
The secondary air injection system, which pumps air into the exhaust during cold starts, is not flowing as expected.
Generic OBD-II definition: Secondary Air Injection System Incorrect Flow Detected. Confirm applicability in your vehicle service information.
Common causes
- Failed air pump
- Stuck check valve
- Blocked passages
- Blown fuse or bad relay
Symptoms
- Loud pump noise on cold start
- Often no drivability symptoms
Can I keep driving with P0411?
Severity: Low Usually safe to keep driving, but get it checked.
If the check engine light is flashing or the car runs badly, stop driving and have it checked.
Typical fixes
- Check fuse and relay
- Test air pump
- Inspect check valves