P0411
Low SeveritySecondary Air Injection System Incorrect Flow
Emissions System
What Does P0411 Mean?
The secondary air injection system is not flowing properly. This system pumps fresh air into the exhaust on cold starts to help the cat warm up.
Common Fix
Replace check valve or air pump
Estimated Cost (DIY)
$30 - $300
Symptoms
- ⚠️Check engine light
- ⚠️Failed emissions test
- ⚠️Slight noise from air pump on cold start
Common Causes
Failed air pumppossible
Stuck check valvelikely
Clogged air injection passagespossible
Relay or fuse issuepossible
How to Diagnose P0411
- 1Check air pump relay and fuse
- 2Listen for air pump on cold start
- 3Inspect check valve for sticking
- 4Check passages for carbon blockage
Need to read or clear this code?
Shop OBD2 Scanners on Amazon →Frequently Asked Questions
- What is secondary air injection?
- It pumps fresh air into the exhaust manifold on cold starts to help the catalytic converter reach operating temperature faster.
- Is P0411 expensive to fix?
- The check valve is cheap ($30-$50). If the air pump has failed, it can be $150-$300 for the pump.