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.
2021 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE
Exhaust Side
- Disconnect the ground cable from battery.
- Lift up the vehicle.
- Remove the under cover. Refer to EXTERIOR/INTERIOR TRIM>FRONT UNDER COVER>REMOVAL .
- Remove the front exhaust pipe. (Right side only.) Refer to EXHAUST(STI)>FRONT EXHAUST PIPE>REMOVAL .
- Remove the engine harness cover. (Right side only.)
- Remove the clip holding the engine harness. (Left side only)
- Disconnect the ground cable (A). (Left side only)
- Disconnect the connector (B) from the oil flow control solenoid valve, and remove the oil flow control solenoid valve from the cylinder head.
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.