P0456 on Your 2020 Impreza: The Evidence
Your 2020 Impreza (5th generation) has triggered P0456—a very small EVAP leak. The 2.0L Boxer with Symmetrical AWD uses a traditional gas cap and standard EVAP system. Basic warranty expired, but federal emissions (8yr/80k) covers EVAP through 2028.
Clues
- Check engine light on
- P0456 stored
- No drivability symptoms
- Gas cap may show wear after 5+ years
Suspects
- Gas Cap Seal (High Likelihood): Five years of wear. $10–$15.
- Purge Control Solenoid Valve (High Likelihood): Known Subaru EVAP failure. Under emissions warranty or $80–$190.
- Canister Vent Valve (Medium Likelihood): Age-related wear. Under emissions warranty or $90–$210.
- EVAP Hose (Medium Likelihood): Rubber deterioration. $100–$220.
- Charcoal Canister (Low Likelihood): Fuel overfilling damage. $180–$350.
Diagnostic Steps
- Replace gas cap—$10–$15
- Clear code, drive 2–3 cycles
- Check federal emissions warranty—8yr/80k through 2028
- Dealer appointment—ask about EVAP TSBs
- Smoke test if out-of-pocket ($80–$150)
Costs
- Gas cap: $10–$15
- Purge valve: $80–$190 (may be emissions covered)
- Canister vent valve: $90–$210
- Federal emissions 8yr/80k through 2028
Can I Drive?
Yes. P0456 has zero impact on the 2.0L Boxer, AWD, or safety.
Warranty
Basic 3yr/36k expired. Powertrain 5yr/60k expired. Federal emissions 8yr/80k covers EVAP through 2028. Ask dealer about applicable TSBs.