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Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0455 EVAP system large leak detected

Can I drive with P0455?

Drive

Safe to keep driving normally. Fix it when convenient.

It only affects fuel-vapor emissions, not how the engine runs. You may smell fuel near the car, and the light stays on until the leak is fixed, which matters if your state requires an emissions inspection.

What does P0455 mean?

The fuel vapor system found a large leak. The most common reason is a gas cap that is missing or not tightened. The system traps gasoline vapor from the tank and burns it in the engine instead of letting it escape into the air.

What causes P0455?

Start with the gas cap, since it is the most common cause. If the cap is fine, a hose or valve is next.

  1. Gas cap loose or missing
  2. Cracked or disconnected EVAP hose
  3. Purge valve stuck open
  4. Faulty vent valve
  5. Damaged charcoal canister

How much does it cost to fix P0455?

$0 – $600

Tighten or replace the gas cap first ($0–$60). Hoses and valves: $100–$400. If the cap is not the problem, a shop smoke test pushes visible vapor into the system to show exactly where it escapes, so you only pay for the part that failed.

What are the symptoms of P0455, and how can I confirm it?

Usually none besides the light; some drivers smell fuel after refueling. Check that the cap is there, its seal is not cracked, and it clicks when tightened. Then look for split or loose hoses near the tank and charcoal canister. P0442, P0456 and P0457 come from the same leak test.

Will P0455 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on, and the EVAP monitor must finish too. Tighten or replace the cap, then clear the code or keep driving; the light often turns off by itself. If P0455 returns after several days of normal driving, find the leak.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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