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P0455 EVAP System Large Leak Detected

What it means

The EVAP system detected a large leak — often a missing or loose gas cap.

Severity: Low

Can I drive it? Safe to drive; you may notice a fuel smell.

Common causes (most likely first)

Gas cap missing, loose, or bad seal
Disconnected or cracked EVAP hose
Stuck-open purge valve
Damaged canister or filler neck

Likely fixes

Check/replace gas cap
Inspect hoses near tank and canister
Smoke-test EVAP system

DIY parts cost

$15–$250

Approximate estimate

Shop repair cost

$100–$600

Approximate estimate, parts + labor

DIY difficulty

Easy

Varies by vehicle

Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.

Parts you may need

Gas capCheck price
EVAP purge valveCheck price
EVAP hoseCheck price
Charcoal canisterCheck price

Affiliate links are placeholders. Verify fitment for your year/make/model.