P0440

Evaporative Emission Control System Malfunction

Severity: moderate Driveability: Safe To Drive AI generated

Plain-English meaning

The vehicle's onboard diagnostic system has detected a problem in the evaporative emission control system (EVAP), which is responsible for preventing fuel vapors from escaping into the atmosphere.

What to check first

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What not to replace yet

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Stop driving when

It is generally safe to continue driving; however, if you notice fuel odors, fuel leaks, or significant drivability issues, stop driving and have the vehicle inspected.

Related symptoms

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Owner steps

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Likely causes

Loose or missing gas cap (medium)

Faulty or damaged gas cap seal (medium)

Leaking or cracked EVAP hoses or lines (medium)

Faulty purge valve or vent valve (medium)

Defective charcoal canister (medium)

Electrical issues in EVAP system sensors or wiring (medium)

Shop steps

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Follow-up questions

Have you recently refueled the vehicle and checked the gas cap?

Is the Check Engine Light steady or flashing?

Have you noticed any fuel odors or leaks?

Has the vehicle failed any recent emissions tests?