P0410: Secondary Air Injection System Malfunction
Key takeaways
- P0410 is the general secondary air injection fault: the system that blows air into the exhaust for the first minute or two after a cold start isn't working as the computer expects.
- It's an emissions code: the car drives normally and is safe to drive, but it will fail an emissions or plug-in inspection.
- A seized air pump, a stuck or corroded check valve and a blown fuse or failed relay are the usual causes.
- P0410 repairs at a US independent shop run from $20–$150 for a fuse or relay to $400–$1,000 for a new air pump.
What P0410 means
The system that blows fresh air into your exhaust right after a cold start has a fault the computer can’t pin down more precisely.
Scanners call it “Secondary Air Injection System Malfunction.” Many cars have an electric air pump, a check valve (sometimes called a switching or combination valve) and hoses that feed air into the exhaust manifold or cylinder head for the first minute or two after a cold start. The extra oxygen burns off the rich cold-start exhaust and warms the catalytic converter. The computer checks the system by watching the upstream oxygen sensor go lean when the pump runs, or on some cars by reading a dedicated air pressure sensor. When the result doesn’t fit, it sets P0410. Some makes use P0410 for the same faults others report as P0411.
Is it safe to drive?
Yes. The system only works in the first minutes after a cold start and does nothing once the engine is warm. You won’t feel a difference, but the car will fail an emissions or plug-in inspection.
The symptom that changes the answer: a pump that keeps whining after the engine is warm. That usually means a relay stuck on, and the pump will cook itself. Pull the pump fuse or relay and book it in. A rough idle along with P0410 points to a second problem; read rough idle.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Air pump seized, weak or full of water | Listen for the pump at cold start; command it with a scan tool; check for water or rust in the pump outlet | $400–$1,000 |
| Check or switching valve stuck or corroded | Exhaust soot or moisture in the hose on the pump side; valve doesn’t open on vacuum or command | $150–$500 |
| Blown fuse or failed pump relay | Check the fuse; swap the relay with an identical one; test for power at the pump plug | $20–$150 |
| Cracked, melted or disconnected air hose | Visual check along the hose from pump to valve; listen for a hiss at cold start | $50–$200 |
| Wiring or connector at the pump or valve | Power and ground test at the plug with the pump commanded on | $100–$250 |
| Carbon-clogged air passages in the head or manifold | Pump and valve test good but the system still fails; passages blocked on inspection | $300–$1,000 |
What to check first
- Listen at a true cold start. Let the car sit overnight. A working pump runs for roughly a minute and then stops. Silence, grinding or a pump that never stops each point somewhere different.
- Check the fuse and relay. It’s the cheapest fix and it takes five minutes.
- Look at the hoses between the pump and the check valve. Water or black soot on the pump side means the check valve is letting exhaust back through, which also kills pumps.
- Command the pump and valve with a scan tool and watch the oxygen sensor go lean. A good shop does this before replacing anything.
- Replace the check valve with the pump when the valve has let moisture through, or the new pump fails the same way.
NHTSA’s manufacturer communications files for 2015–2024 hold no bulletins naming P0410, so there’s no known software fix to look for. Of the 11 owner complaints that mention the code, 3 are for the Subaru Impreza, across the 2006, 2013 and 2014 model years; that’s a count of owner reports, not a confirmed defect. The system is only tested after a cold start, so after a repair, clear the code and drive for a few days of cold starts to confirm.
What it costs
The cheap outcome is a fuse or relay, $20–$150. The common outcome is a check valve at $150–$500, or a pump at $400–$1,000, sometimes both. The expensive outcome is a pump and valve together, or passages clogged with carbon, which can push past $1,000 on some engines. A cold-start test with a scan tool tells you which part failed before you pay for two. If you’d like help reading the symptoms, ask in the chat.
Related codes
P0411 is the incorrect-flow version of this fault and often shows up with P0410. P0412 and P0418 are the switching valve and pump relay circuits, and P0414 is the switching valve circuit shorted. If the light goes off and back on between cold starts, see check engine light comes on and off.
What owners report to NHTSA
11 complaints filed with NHTSA mention P0410, 6 of them since 2015, across 9 different models. The component owners most often filed it under: engine and engine cooling.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| SUBARU IMPREZA | 3 | 2006, 2013, 2014 |
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
What does the secondary air injection system do?
For the first minute or two after a cold start it blows fresh air into the exhaust. That extra oxygen burns off the rich cold-start exhaust and heats the catalytic converter faster. After that it shuts off until the next cold start.
Can I drive with a P0410 code?
Yes. The system only runs briefly at cold start and has no effect on how the car drives once warm. You'll fail an emissions inspection, and the light hides any new fault, so plan the repair.
What is the difference between P0410 and P0411?
P0410 is the general secondary air fault; P0411 says the computer measured too little airflow. Many cars set P0410 for the same problems, a dead pump, a stuck valve or a blown fuse, so the diagnosis starts the same way.
Why does P0410 come back after the pump is replaced?
Usually because the check valve was letting exhaust and moisture back into the pump, and the new pump fails the same way. Replace or test the check valve with the pump, and check the fuse and relay.