Evap Leak Detected in 2015 Chevrolet Traverse - How to Fix It Step by Step

Model: Chevy Traverse Fault Code: P2177 Posted: 2019-01-23 10:08

I'm completely stuck trying to resolve a persistent evaporative emissions (EVAP) system leak on my wife's 2015 Chevrolet Traverse. The vehicle initially flagged a faulty mass air flow (MAF) sensor, which I replaced—however, the issue persisted. Next, the check engine light triggered an EVAP system leak code. I replaced both the purge solenoid and the fuel vapor canister located on the gas tank, but neither fix resolved the problem. The vehicle occasionally displays a 'tighten gas cap' warning even when the cap is securely fastened. After replacing the gas cap, the check engine light remains on with an ongoing EVAP leak diagnosis. I'm now looking for guidance on what the next troubleshooting steps should be—especially since all standard parts have been replaced. Can anyone confirm which specific diagnostic code (e.g., P0441 or similar) is being triggered by this issue? Any insights into potential underlying causes would be greatly appreciated.