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Common codes
P0420P0300P0171P0455P0442P0128P0401P0113

P0440: Evaporative emission control system malfunction

You can keep driving. Get it checked when convenient.

Can I drive with P0440?

Yes, you can keep driving. Evaporative emissions leak or pressure fault; usually safe to drive for a short time, but get it checked to keep driving.

What does P0440 mean?

P0440 stands for Evaporative Emission Control System Malfunction.

Symptoms you may notice

  • Steady check engine light with minimal drivability symptoms
  • Normal engine power, idle, and acceleration
  • Possible faint gasoline vapor smell near gas cap

How much does it cost to fix?

Repair costs for code P0440 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:

  • Loose, cracked, or worn fuel filler gas cap
    $10-$30 common
  • Faulty purge control valve
    $40-$120 possible
  • Cracked rubber EVAP vapor hose
    $20-$60 possible
  • Damaged charcoal canister
    $150-$400 rare

What to do next

  1. Remove and re-tighten your gas cap until it clicks 3 times.
  2. Inspect the rubber seal on the inside of the gas cap for cracks.
  3. Clear the code with a scanner; if it stays off, the gas cap was the issue.
Last updated: October 2026

Related codes

P0442 P0455 P0446 P0456
General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.

About this code

Code P0440 indicates that the fuel vapor containment system failed a vacuum pressure test. The EVAP system traps gasoline fumes in a charcoal canister rather than venting them into the open air. This issue rarely causes the vehicle to hesitate or stall. You can drive normally in the short term, though you must fix it before passing emissions inspections.