P0455 — Evaporative Emission System Large Leak Detected

P0455 means there's a large leak in your fuel vapor (EVAP) system. The #1 cause is a loose, missing or cracked gas cap — tighten it first before spending any money.

Cost range: $0–$500. Severity: low. Safe to drive? Yes, P0455 doesn't affect drivability — but you'll fail emissions testing.

Most common causes of P0455

1. Loose or bad gas cap — Tighten until it clicks 3 times. If light persists 50 miles, replace cap (~$15). ($0–$25)
2. Cracked EVAP hose — Inspect rubber hoses near the gas tank and engine bay. ($20–$150)
3. Faulty purge or vent valve — Solenoid stuck open or closed. ($80–$300)
4. Damaged charcoal canister — Less common but possible after rear-end damage. ($200–$500)

Symptoms drivers report with P0455

• Check engine light only
• Possible fuel smell