Guide step
Start with the gas cap
Verify cap seal condition, proper tightening, and neck damage before deeper tests.
Guide page
EVAP Small Leak Checklist Before Replacing Parts
Use this EVAP small leak checklist to narrow gas cap, hose, purge, vent, and smoke-test clues before buying parts.
Guide step
Inspect purge and vent lines
Cracked hoses and sticky purge valves are common on aging vehicles.
Guide step
Use smoke testing when available
A smoke test is often the fastest way to confirm a small leak without guessing.