P0411 Code: Secondary Air Injection — Causes & Fix
P0411 means the secondary air injection system is delivering incorrect airflow — the system that pumps air into the exhaust on cold start to reduce emissions.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $50 – $800
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a failed air pump, a stuck air switching/check valve, or carbon blockage in the passages. P0411 is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer petrol car or light truck regardless of make. Fix the underlying fault, then clear the code with an OBD-II scan tool — it will return if the problem isn't resolved.
Symptoms
- Check engine light on
- Usually no drivability effect
- May fail emissions
How to fix it
- 1
Test the air pump and valve
1. Confirm the secondary air pump runs on cold start. 2. Check the air switching/check valve for sticking.
- 2
Clear blockages
1. Inspect the air passages for carbon. 2. Repair or replace parts, then clear the code.
Frequently asked questions
Is P0411 serious?
It rarely affects driving, but it is an emissions system fault and will fail inspection, so it should be repaired.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.