P0456: Evaporative emission system very small leak detected
You can keep driving. Get it checked when convenient.
Can I drive with P0456?
Yes, you can keep driving. A tiny 0.020-inch vapor leak exists; usually safe to drive for a short time, but get it checked to keep driving.
What does P0456 mean?
P0456 stands for Evaporative Emission Control System Leak Detected (very small leak).
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 P0456 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:
- Slightly cracked or dirty gas cap rubber seal
- Hairline crack in plastic EVAP vapor line
- Leaking purge valve or vent solenoid o-ring
- Slight rust pitting on fuel filler neck lip
What to do next
- Wipe the gas cap rubber O-ring clean with a paper towel and re-tighten firmly.
- Inspect the metal rim of the filler neck for grime or rust specks.
- Replace the gas cap if the seal feels hard or cracked.
Last updated: October 2026
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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 P0456 indicates an extremely small evaporative leak (0.020 inches, smaller than the tip of a toothpick). Modern emissions monitors use sensitive vacuum decay methods to spot microscopic vapor seepage. The vehicle will drive normally for a short time, but get it checked.