P0410 on Subaru: How to Diagnose & Fix
Secondary Air Injection System Malfunction
2 Subaru models · 2 documented issues · 1 critical · $600-$2,200 repair
P0410 on Subaru by model: symptoms, diagnosis and fix
Subaru WRX STI models equipped with the EJ257 and secondary air injection commonly develop failures of the air pump and/or the air switching valves, often due to moisture intrusion and internal corrosion that causes the valves to stick. Owners typically see a check engine light with cold-start drivability changes and may fail emissions/inspection due to stored air injection codes. This issue is widely documented in owner reports and Subaru service information/TSBs covering secondary air injection diagnostics and component replacement.
Common Symptoms
- Check Engine Light on after cold start
- DTCs P0410, P2440/P2441/P2442/P2443 stored
- Rough or high idle on cold start
- Failed emissions/inspection readiness
- Whining or abnormal noise from air pump area
How to Fix
Diagnose with scan tool and active tests; replace failed air pump and/or air switching valves and related hoses/gaskets. Common components include the secondary air pump and air switching valves (bank-specific); replace any water-damaged connectors and ensure updated routing/sealing per Subaru service guidance (refer to Subaru TSBs addressing secondary air injection DTCs for applicable years).
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (1)
On turbocharged Forester XT models, the relay controlling the secondary air injection (SAI) pump can fail in the closed position, leaving the air pump running continuously. Sustained operation overheats the pump, which can melt surrounding components and create a fire risk even with the vehicle parked. Subaru recalled about 100,000 turbo vehicles (Forester XT, Impreza WRX/STI, Legacy/Outback turbo) for the defect.
Common Symptoms
- Burning / melting smell from engine bay
- Air pump audibly running after engine warmed up or off
- Check engine light with SAI codes
- Blown SAI-circuit fuse
How to Fix
Free recall repair under Subaru campaign WTM-73 (NHTSA 16V-738): the dealer replaces the secondary air injection pump relay. If the pump itself was already damaged by prolonged overheating it is replaced as well. Owners of turbo XT models should confirm the recall has been completed by VIN, as completion rates on older vehicles are often incomplete.
Sources for this issue (3)
P0410 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0410 mean on a Subaru?
P0410 stands for "Secondary Air Injection System Malfunction." P0410 indicates the engine computer detected a malfunction in the secondary air injection system, which pumps fresh air into the exhaust during cold starts to help the catalytic converter heat up and burn off pollutants faster. The system uses an air pump, valves, and hoses, and the computer monitors whether the expected airflow and resulting oxygen-sensor response actually occur. When the system doesn't perform as commanded — too little or no airflow detected — it sets this code. It generally points to a failed pump or stuck valve and primarily affects emissions, especially during the first minutes after a cold start. On Subaru it is documented across 2 models: WRX STI, Forester.
What are the most common causes of P0410?
The most common causes of P0410 are: Failed secondary air injection pump (seized or worn motor), Stuck or faulty air injection / check valve, Vacuum or electrical control problem to the air switching valve, Cracked, disconnected, or clogged air injection hoses, Moisture or corrosion damage inside the air pump, Blown fuse or relay for the air pump, Faulty wiring or connector in the air injection circuit. The specific cause varies by vehicle.
How much does it cost to fix P0410 on a Subaru?
Published repair estimates on Subaru range from $600 to $2,200 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0410 on a different make?
View P0410 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.