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P0456: Evaporative Emission System Leak Detected (Very Small Leak)
Severity: Low Usually safe to keep driving, but get it checked.
What does P0456 mean?
The EVAP self-test found a very small leak. These can be hard to find and usually need a smoke test.
Generic OBD-II definition: Evaporative Emission System Leak Detected (Very Small Leak). Confirm applicability in your vehicle service information.
Common causes
- Loose, damaged, or wrong gas cap
- Cracked EVAP hose
- Leaking purge or vent valve
- Damaged charcoal canister
- Leaking filler neck
Symptoms
- Usually no drivability symptoms
- Possible faint fuel smell
- Will likely fail an emissions inspection
Can I keep driving with P0456?
Severity: Low Usually safe to keep driving, but get it checked.
If the check engine light is flashing or the car runs badly, stop driving and have it checked.
Typical fixes
- Tighten or replace the gas cap first, then clear the code and drive a few days
- Have a smoke test done to locate leaks
- Test purge and vent valves