Cracking the P0440 Case on Your 2022 Subaru WRX
A P0440 code on your 2022 Subaru WRX points to an EVAP system malfunction. The all-new fifth-generation WRX (VB platform) features a 2.4L turbo Boxer four-cylinder (271 hp) paired with either a 6-speed manual or Subaru Performance Transmission (SPT) CVT, with standard Symmetrical AWD. With a few years of spirited driving under its belt, certain EVAP components may need attention. Let's follow the trail.
Symptoms
- Check engine light on
- Faint gasoline odor
- Slight MPG decrease
- Fueling difficulties at the pump
- Emissions test failure
Your WRX drives normally. The 2.4L turbo, manual/SPT transmission, and AWD are completely unaffected. Full boost and power are available.
Most Likely Causes
- Gas Cap — Worn seal or loose. Always check first. Estimated repair: $5–$25.
- Purge Control Valve — The purge solenoid on the 2.4L turbo can stick. Common issue on turbocharged Subarus. Estimated repair: $75–$200.
- Vent Control Valve — Controls airflow near the charcoal canister. Estimated repair: $80–$215.
- Vapor Line Leak — The WRX's higher underhood temperatures from the turbo can accelerate hose wear. Estimated repair: $45–$140.
- Aftermarket Intake/Tune Effects — If your WRX is modified, aftermarket parts can affect EVAP system operation. Estimated repair: varies.
Diagnostic Steps
- Replace gas cap, clear code, drive 50+ miles
- Scan for companion EVAP codes
- Check for aftermarket modifications that may affect EVAP
- Test purge and vent valves with bidirectional scan tool
- Perform EVAP smoke test
Repair Costs
- Gas cap: $5–$25
- Purge control valve: $75–$200
- Vent control valve: $80–$215
- Vapor line: $45–$140
- Diagnostic: $80–$150
Warranty: Subaru's 3-year/36,000-mile basic warranty has likely expired. Note: modifications may void warranty coverage on affected components.
Can I Drive With P0440?
Yes. P0440 has zero impact on boost, power, AWD, or driving dynamics. Full performance is available.
DIY Feasibility
Gas cap is trivial. WRX owners tend to be hands-on. The purge valve on the 2.4L turbo is moderately accessible. The vent valve underneath requires more effort. If you have aftermarket parts, ensure EVAP connections aren't disturbed.