P0411 on Audi: Secondary Air Injection System Incorrect Flow Detected
Diagnostic trouble code P0411 on Audi vehicles — what it means, the common
causes, and how to confirm the real fault before replacing parts.
What does P0411 mean?
P0411 indicates: Secondary Air Injection System Incorrect Flow Detected.
This relates to the Emissions / auxiliary emission controls system.
Common causes of P0411
Blockage (restricted flow) downstream of secondary air injection sensor G609
Reduced pumping capacity of secondary air pump
Blockage upstream of secondary air injection sensor 1 G609
Leak in the secondary air system
Faulty pressure sensor (Secondary Air Injection Sensor 1 G609)
Combination valve stuck open or not operating correctly
Ingress of dirt into the system downstream of the pressure sensor
What to check (live data)
Signal from Secondary Air Injection Sensor 1 G609 (pressure level in secondary air system; expected rise to approx. 90 mbar above atmospheric during injection phase)
Ambient pressure sensor signal (compared to G609 signal during Phase 0 initialization)
Intake manifold pressure sensor signal (compared to G609 signal during Phase 0 initialization)
Pressure difference over time across diagnostic phases (Phases 0 through 7)
Parts often involved in P0411
Secondary Air Injection Sensor 1 G609 (pressure sensor)
Secondary air pump
Combination valve (secondary air valve)
Don't replace parts until the root cause is confirmed — many of these codes are caused by wiring, a connector or an upstream fault, not the part itself.
Get the confirmed root cause for P0411 — on YOUR vehicle
A code is a symptom, not a diagnosis. AutoDX Pro cross-checks several
independent assessments, pinpoints the actual root cause, gives you the
exact tests to confirm it, and shows the parts — only after the cause is
confirmed. Reads your scan-tool photo and decodes your VIN with open
recalls.
P0411 is a diagnostic trouble code: Secondary Air Injection System Incorrect Flow Detected.
What are the common causes of P0411 on an Audi?
Common causes include: Blockage (restricted flow) downstream of secondary air injection sensor G609, Reduced pumping capacity of secondary air pump, Blockage upstream of secondary air injection sensor 1 G609, Leak in the secondary air system. The exact cause depends on the vehicle — confirm it before replacing parts.
Can I keep driving an Audi with P0411?
It depends on the fault and your symptoms. Some causes are minor, others can damage components or affect safety. Get the root cause confirmed before deciding.
How do I fix P0411 on an Audi?
Confirm the actual root cause with targeted tests first, then replace only the part that's at fault. AutoDX Pro gives you the root cause, the exact tests, and the parts for P0411 on your specific Audi.