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
Most Reported On
P2431 is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2006-2014 Subaru WRX, with repair costs ranging from $700 to $2,200.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P2431, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
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.