P0411: Secondary air injection incorrect flow detected
The ECU sees that secondary air is not reaching the exhaust properly after a cold start. Usually a stuck valve, a split hose or the pump.
| Code | P0411 |
|---|---|
| System | Engine and transmission |
| Group | P04xx, Emissions control |
| Type | Generic: it means the same on every make |
| Can you keep driving? | Yes, no rush |
What P0411 means
After a cold start, the secondary air pump pushes air into the exhaust and the oxygen sensor should detect a lean mixture. If the sensor does not see it, or sees it when it should not, the ECU stores this code.
Most common causes
- Check valve stuck with carbon
- Loose or split secondary air hose
- Weak air pump or water inside it
- Switching valve that does not open or close
- Blocked air passages in the cylinder head
- Slow oxygen sensor that fails to detect the air
Symptoms
- Engine warning light on
- Pump sounds different from normal
- Failing an emissions test
- Usually no change in how the car drives
Can you drive with P0411?
Yes, no rush It only affects the first few minutes from cold, so you can drive normally. Worth fixing before the next inspection.
Open the bonnetthe in-depth explanation
How to check it
On a cold start, watch the upstream oxygen sensor voltage on your reader: with secondary air working it should stay low (lean) for the first minute.
How to read and clear P0411 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0411 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P040D The exhaust gas recirculation temperature sensor A gives a higher signal than
- P040E The exhaust gas recirculation temperature sensor A fails now and then
- P040F EGR temperature sensors A and B do not agree
- P0410 Secondary air injection system malfunction
- P0412 Secondary air switching valve A circuit malfunction
- P0413 The secondary air injection system switching valve A has a broken or
- P0414 The secondary air injection system switching valve A has a short circuit
- P0415 The secondary air injection system switching valve B has an electrical fault
- P0400 Exhaust gas recirculation (EGR) flow malfunction
- P0401 Exhaust gas recirculation (EGR) flow insufficient
- P0402 Exhaust gas recirculation (EGR) flow excessive
- P0403 EGR control circuit malfunction
What does code P0411 mean?
After a cold start, the secondary air pump pushes air into the exhaust and the oxygen sensor should detect a lean mixture. If the sensor does not see it, or sees it when it should not, the ECU stores this code.
Can you drive with P0411?
It only affects the first few minutes from cold, so you can drive normally. Worth fixing before the next inspection.
How do you clear P0411?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0411 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
