P0455 GMC Terrain
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 GMC Terrain 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 GMC Terrain.
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 GMC Terrain.
Common Causes on GMC Terrain
- Gas cap missing or severely damaged
- EVAP vent solenoid stuck open
- EVAP purge solenoid stuck open causing large leak
- Disconnected EVAP vapor hose at charcoal canister
- Fuel tank seal failure
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 GMC Terrain
On Equinox and Terrain, a stuck-open EVAP vent solenoid is the most common cause of P0455 after a missing or loose gas cap.