P2431 on 2006-2014 Subaru WRX — Secondary Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance (Bank 1)
1 vehicles · 1 makes · $700-$2,200 repair
How to diagnose and fix P2431: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Subaru WRX · 2006–2014
Turbo EJ255/EJ257 WRX models equipped with the secondary air injection system commonly develop failures of the air pump, pressure sensor, or the air switching valves. Moisture intrusion and corrosion can cause the valves to stick or the pump to seize, which sets emissions faults and on many cars can reduce power or force a limp-home condition. Owners typically report a check-engine light shortly after cold start, often with rough cold operation or an audible pump noise before failure.
Common Symptoms
- check engine light after cold start
- reduced power or limp mode
- loud buzzing or whining from air pump area
- rough cold start
- failed emissions inspection
How to Fix
Diagnosis usually starts with scanning for secondary air system codes and commanding the pump/valves with a capable scan tool. Repair typically involves replacing one or both air switching valves, the pump, and sometimes the pressure sensor or related hoses; some owners also inspect for water entry and update gaskets/hoses during repair. Because access is tight on turbo models, labor can be significant, and clearing codes without fixing the root cause usually results in repeat faults.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Subaru 14828AA060 Secondary Air Pump Assembly
early pump branch only after bidirectional testing proves the pump itself failed Fitment/availability: 2007 WRX and 2007 STI turbo secondary-air system; also cataloged for 2007-2008 Forester XT, confirm VIN Fitment/availability: Ships di…
- Genuine Subaru 14828AA050 Secondary Air Injection Pump Assembly
later pump branch only after bidirectional testing proves the pump itself failed Fitment/availability: 2008-2014 WRX and 2008-2021 STI; this canonical card uses it only for the 2008-2014 WRX/STI overlap, confirm VIN Fitment/availability:…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipUse an OBD-II scanner that can read Subaru-specific pending/history codes and active test the air pump/valves before buying parts.
Find P2431 by make
Browse every documented model and issue for your make.
P2431 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 P2431 mean?
P2431 stands for "Secondary Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance (Bank 1)." This code means the engine computer detected that the secondary air injection (SAI) system airflow or pressure sensor on Bank 1 is reading outside its expected range. The SAI system pumps fresh air into the exhaust during cold starts to help burn off excess hydrocarbons and reduce emissions while the catalyst warms up. An out-of-range sensor reading means the computer can't verify the system is delivering the correct amount of air. It mainly affects cold-start emissions and is not an immediate driving hazard, but should be repaired to pass inspections.
What are the most common causes of P2431?
The most common causes of P2431 are: Faulty secondary air injection pressure/flow sensor, Stuck or faulty secondary air injection pump, Clogged or leaking air injection passages/hoses, Faulty air switching/check valve, Wiring or connector fault at the sensor, Carbon buildup restricting airflow. The specific cause varies by vehicle.
How much does it cost to fix P2431?
Repair costs for P2431 range from $700 to $2,200, depending on the vehicle and root cause.
Which vehicles are affected by P2431?
Au7o has documented P2431 across 1 vehicle models from 1 manufacturers: Subaru.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.