P0440: Evaporative Emission System Malfunction
The EVAP system, which traps fuel vapor from the tank, has a problem. It doesn't affect how the engine runs.
Green, yellow, red: three ways P0440 can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
Light on, no fuel smell. Tighten the gas cap and drive normally for a few days.
Schedule a repair
Code returns after a new cap, or you need to pass inspection. Schedule a smoke test.
Stop and get help
Strong raw fuel smell or a visible fuel leak. Don't drive it; that's a fire risk.
Symptoms you might notice
- Usually none
- Occasional fuel smell
Common causes, cheapest first
- Loose or worn gas cap
- Cracked EVAP hose
- Purge or vent valve problem
- Leaking charcoal canister
What you can check before calling
- Tighten the gas cap until it clicks, or replace a worn cap
- Smell for fuel vapor near the tank
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Want the full story? Read our guide: Check engine light after getting gas? Gas caps and EVAP codes.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
Related codes
More evap (fuel vapor) codes
- P0441
Evaporative Emission System Incorrect Purge Flow - P0446
Evaporative Emission System Vent Control Circuit Malfunction - P0449
Evaporative Emission System Vent Valve/Solenoid Circuit Malfunction - P0457
Evaporative Emission System Leak Detected (Fuel Cap Loose/Off) - P0496
Evaporative Emission System High Purge Flow
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P0440 mean?
P0440 means "Evaporative Emission System Malfunction". The EVAP system, which traps fuel vapor from the tank, has a problem. It doesn't affect how the engine runs.
Can I drive with code P0440?
It depends on what the vehicle is doing. Green: Light on, no fuel smell. Tighten the gas cap and drive normally for a few days. Yellow: Code returns after a new cap, or you need to pass inspection. Schedule a smoke test. Red: Strong raw fuel smell or a visible fuel leak. Don't drive it; that's a fire risk.
What causes P0440?
The most common causes are: loose or worn gas cap; cracked EVAP hose; purge or vent valve problem.
Is P0440 a serious code?
It can be. Strong raw fuel smell or a visible fuel leak. Don't drive it; that's a fire risk.
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