P0440 OBD-II code — what it means and what to check

ℹ Guidance only — not a substitute for inspection

Enter the trouble codes from your scanner to see what each one means, how urgent it is, and which checks to do first.

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Your trouble codes

Enter the codes exactly as your scanner shows them. Separate several codes with spaces or commas.

A letter followed by four characters, for example P0301. Up to ten codes at a time.
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Your codes, interpreted

What this means
⚠ Book a service. The codes you entered describe faults that get worse, or more expensive, if left.
What to doBook a workshop inspection. Normal driving is usual with these faults, but they should not be left indefinitely.

Your codes

  1. P0440 — Emissions control (service soon). A general fault in the evaporative emissions system, which contains fuel vapour. This is the broadest EVAP code — it says something is wrong without saying what.

Checks to do first, in order

  1. Check the fuel filler cap first: present, correct type, undamaged seal, properly tightened.
  2. Look for more specific EVAP codes stored alongside it — those will point somewhere this one cannot.
  3. Inspect the EVAP hoses and the charcoal canister for cracks or disconnection.
  4. Have a smoke test done if nothing obvious turns up.

Codes this tool cannot interpret

How this result was reached
  • Interpretations cover standardised codes only, and describe what a code means rather than what is wrong with your specific vehicle.
  • A stored code identifies the circuit or system reporting a fault. It does not identify the failed part — a sensor commonly reports a problem it did not cause.
  • Reviewed by Project Owner on 2026-08-26.
  • This tool covers a reviewed subset of standardised codes. A code it does not recognise is reported as undocumented rather than guessed at.