P0455 Subaru Outback
EVAP System Leak Detected (Gross Leak) · Powertrain Code · Medium · Repair: Easy
What is P0455?
A large leak has been detected in the EVAP system. Check gas cap first — if secure, look for disconnected or cracked EVAP hoses, a stuck-open purge valve, or a leaking charcoal canister.
When the Subaru Outback triggers code P0455 (evap system leak detected (gross leak)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Subaru Outback.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Subaru Outback.
Common Causes on Subaru Outback
- Gas cap missing or completely worn out
- EVAP purge valve stuck wide open
- EVAP hose connection completely disconnected at charcoal canister
- Fuel filler neck severe corrosion causing large leak
- Charcoal canister housing cracked
Symptoms
- Check engine light illuminated
- Noticeable fuel smell near vehicle
- Gas cap warning light on dashboard
- Failed emissions test
- Fuel economy noticeably decreased
Notes for Subaru Outback
Subaru EVAP hose connections at the charcoal canister can work loose over time on Outback, Forester, Crosstrek, Impreza, and Ascent.