P2443 on Subaru: How to Diagnose & Fix
Secondary Air Injection System Switching Valve Stuck Closed (Bank 2)
1 Subaru model · 1 documented issue · $600-$2,200 repair
P2443 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.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
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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)
P2443 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 P2443 mean on a Subaru?
P2443 stands for "Secondary Air Injection System Switching Valve Stuck Closed (Bank 2)." This code is part of your car's emissions system. The secondary air injection system pumps fresh air into the exhaust right after a cold start to help the catalytic converter heat up and burn off pollutants faster. P2443 means the switching (changeover) valve that controls this airflow on Bank 2 — the side of the engine that does NOT contain cylinder 1 on a V-style engine — appears stuck in the closed position, so the expected air isn't reaching the exhaust. The computer detected this either by monitoring air pressure/flow or by seeing the wrong oxygen-sensor response during the cold-start air pump test. It's an emissions and inspection concern rather than something that will strand you. On Subaru it is documented across 1 model: WRX STI.
What are the most common causes of P2443?
The most common causes of P2443 are: Stuck or seized secondary air injection switching/changeover valve (Bank 2), Carbon, moisture or rust buildup inside the valve or air passages, Failed vacuum or electric solenoid that operates the switching valve, Disconnected, cracked or collapsed vacuum hose to the valve, Failed or weak secondary air injection pump, Wiring or connector fault to the valve/solenoid, Clogged combination valve or check valve preventing airflow. The specific cause varies by vehicle.
How much does it cost to fix P2443 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 P2443 on a different make?
View P2443 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.