Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2018 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE
Drive Cycle G
| DTC | Item | Condition |
|---|---|---|
| P0410 | SECONDARY AIR SYSTEM | - |
| P0411 | SECONDARY AIR SYSTEM INCORRECT FLOW DETECTED | - |
| P0414 | SECONDARY AIR SYSTEM SWITCHING VALVE "A" CIRCUIT SHORTED | - |
| P0417 | SECONDARY AIR SYSTEM SWITCHING VALVE "B" CIRCUIT SHORTED | - |
| P1410 | SECONDARY AIR INJECTION SYSTEM COMBINATION VALVE STUCK OPEN | - |
| P2258 | SECONDARY AIR SYSTEM CONTROL "A" CIRCUIT HIGH | - |
| P2440 | SECONDARY AIR SYSTEM SWITCHING VALVE STUCK OPEN BANK 1 | - |
| P2441 | SECONDARY AIR SYSTEM SWITCHING VALVE STUCK CLOSED BANK 1 | - |
| P2442 | SECONDARY AIR SYSTEM SWITCHING VALVE STUCK OPEN BANK 2 | - |
| P2443 | SECONDARY AIR SYSTEM SWITCHING VALVE STUCK CLOSED BANK 2 | - |
Diagnostic procedure:
- Disconnect the battery negative terminal, and reconnect after at least 10 seconds have passed.
- Idle the engine until engine coolant temperature is 80°C (176°F) more.
- Stop the engine to decrease the engine coolant temperature down to 40°C (104°F) or less.NOTE: Do not let engine coolant temperature drop to 5°C (41°F) or less.
- Idle the engine until engine coolant temperature is 80°C (176°F) more.
- Stop the engine to decrease the engine coolant temperature down to 40°C (104°F) or less.NOTE: Do not let engine coolant temperature drop to 5°C (41°F) or less.
- Idle the engine.
- Read the temporary code using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (STI)>Read Diagnostic Trouble Code (DTC)>OPERATION .
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.