P0411
AIR System A Incorrect Flow Detected
Secondary air injection
Generic OBD-II
Medium
What it means
P0411 means the secondary air injection ("AIR") system isn't delivering the airflow the ECM expects into the exhaust — either too much or too little. That pump only runs for a short time after a cold start to speed up catalyst warm-up, so this won't affect how the car drives. It does keep the check-engine light on and will fail an emissions test.
Medium
Can I keep driving? Safe to drive — the air pump only runs briefly at cold start, so it won't change how the car drives, but it fails emissions and keeps the light on.
Common symptoms
What you'll notice
- Check-engine light on
- Fails an emissions test
- Sometimes a loud air-pump whir on cold start-up
Common causes
Most likely first
- Stuck or leaking check valve letting exhaust back into the pumpLikely
- Failed secondary air injection pump (often from water ingress)Common
- Clogged or broken air injection hose or passageCommon
- Faulty air switching/solenoid valve or its vacuum supplyLess often
- Damaged wiring or connector in the systemLess often
- Rarely, a failing ECMLess often
How to diagnose & fix
Work through it in order
- Reproduce the fault on a cold start and listen for the pump running.
- Inspect the check valve, hoses, and pipes for leaks, clogging, or carbon.
- Test the air switching valve and solenoid actuation.
- Confirm the pump builds airflow; replace it if seized or water-damaged.
- Clear the carbon or replace the failed part, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0411?+
Yes — the secondary air system only works for a minute or two after a cold start, so driveability is unaffected. It will fail emissions until repaired.
Can I just clear P0411?+
It will return the next time the system self-tests on a cold start unless the airflow fault — usually a check valve or pump — is fixed.
Related codes
Often seen with P0411
Read & clear P0411 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX