P0411 Secondary air injection system incorrect flow detected
What P0411 means
The engine control unit monitors the oxygen sensors while the secondary air pump runs after a cold start. If the exhaust does not go lean as expected, it concludes that air flow is too low or not where it should be.
P0411 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 150–1000 €
- Workshop time
- 1–6 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Air pump noisy or silent after a cold start
- Possible rough idle when cold
- Emissions test failure
Common causes
- Weak or failed secondary air pump
- Stuck closed or stuck open check/combination valve
- Blocked or cracked air hoses
- Carbon-blocked air passages in the cylinder head
- Faulty pump relay or vacuum control solenoid
Can I keep driving with P0411?
You can drive, but have it checked within one to two weeks. The fault mainly affects the catalytic converter and emissions.
What to check first
- Confirm the pump runs after a cold start and moves air at the outlet
- Inspect hoses and the check valve for blockage, cracks or soot
- Test the relay and vacuum solenoid that control the valve
- Clean blocked passages or replace the pump or valve
Related codes
- P0410 Secondary air injection system A
- P0406 EGR sensor A circuit high
- P0405 EGR sensor A circuit low
- P0404 EGR A control circuit range/performance
- P0403 EGR A control circuit/open
- P0420 Catalyst system efficiency below threshold (bank 1)
- P0402 EGR flow excessive detected
- P0401 Exhaust gas recirculation (EGR) A flow insufficient
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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