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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.

P0440 Evaporative emission (EVAP) system malfunction

Can I drive with P0440?

Drive

Safe to keep driving normally. Fix it when convenient.

It only affects fuel-vapor emissions, not how the engine runs.

What does P0440 mean?

The system that traps gasoline vapor from the fuel tank has a fault somewhere, either a leak or a valve not working.

What causes P0440?

  1. Loose or faulty gas cap
  2. Faulty EVAP vent valve
  3. Faulty purge valve
  4. Cracked or disconnected EVAP hose
  5. Damaged charcoal canister

How much does it cost to fix P0440?

$100 – $600

Gas cap: $15–$60. Purge or vent valve: $150–$400. Charcoal canister: $300–$600.

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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