P0411: Secondary Air Injection System Incorrect Flow Detected
The secondary air system is running, but the computer does not see the right amount of fresh air reaching the exhaust after a cold start.
What P0411 means
P0411 is more specific than P0410. The computer turns on the air pump during a cold start and watches the upstream oxygen sensors. Fresh air in the exhaust should drive those sensors strongly lean within a few seconds. If they do not respond enough, the computer decides the air flow is incorrect. RepairPal lists defective air management valves, a faulty pump or relay, failed control solenoids and vacuum lines, and passages plugged with carbon as common triggers. On some engines, carbon builds up in the small air ports in the cylinder head, and the fix is cleaning those passages rather than buying a pump. A valve that is stuck closed blocks the air, while one stuck open can let exhaust back into the pump. You usually will not notice any change in driving, but the car may fail an emissions test. Shops check pump output, test the valves and solenoid, and inspect the passages before replacing parts.
Common symptoms
- Check engine light on
- Usually no change in driveability
- Loud or no noise from the air pump on cold start
- Failed emissions test
- Possible hesitation on acceleration
Most common causes
- Air management or check valve stuck
- Weak or failed air pump
- Carbon blocked air passages in the head or manifold
- Faulty air control solenoid or vacuum line
- Failed air pump relay
What to check yourself first
Listen for the air pump on a cold start. Check the hoses from the pump to the valve for cracks or water inside. If your vehicle maker has a service bulletin on clogged air passages, ask the shop about it.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace secondary air control (check) valve | $613-$767 | RepairPal lists defective air management valves as the top cause. |
| Replace secondary air injection pump | $572-$698 | If the pump is weak or seized. |
| Check engine light diagnosis at a shop | $125-$183 | Checks passages for carbon blockage, a known issue on some engines. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
Related repair guides
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- Ram 1500 Ticking on Cold Start? Broken Exhaust Manifold Bolts, Repair Cost and What to Ask
Related codes
- P0410 Secondary Air Injection System
- P0420 Catalyst System Efficiency Below Threshold (Bank 1)
- P0171 System Too Lean (Bank 1)
- P0430 Catalyst System Efficiency Below Threshold (Bank 2)
- P0300 Random/Multiple Cylinder Misfire Detected