P0456: Evaporative Emission System Leak Detected (Very Small Leak)
The EVAP system found a very small leak. Often a gas cap seal or a tiny crack in a hose.
Green, yellow, red: three ways P0456 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, nothing else. Safe to drive.
Schedule a repair
Code returns. Smoke test to find it.
Stop and get help
Fuel smell or visible leak. Don't drive it.
Symptoms you might notice
- Usually none
Common causes, cheapest first
- Gas cap seal
- Small crack in an EVAP hose
- Purge valve seal
What you can check before calling
- Replace the gas cap if it's old
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
- P0440
Evaporative Emission System Malfunction - 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 P0456 mean?
P0456 means "Evaporative Emission System Leak Detected (Very Small Leak)". The EVAP system found a very small leak. Often a gas cap seal or a tiny crack in a hose.
Can I drive with code P0456?
It depends on what the vehicle is doing. Green: Light on, nothing else. Safe to drive. Yellow: Code returns. Smoke test to find it. Red: Fuel smell or visible leak. Don't drive it.
What causes P0456?
The most common causes are: gas cap seal; small crack in an EVAP hose; purge valve seal.
Is P0456 a serious code?
It can be. Fuel smell or visible leak. Don't drive it.
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