P0456: Evaporative emission system leak detected, very small leak

The leak test found a very small leak in the fuel vapour system. The driver usually sees only the engine light.

Likely causes, most common first

  • Worn fuel cap seal
  • Tiny crack in an EVAP hose
  • Slightly leaking valve
  • Leak at a canister or tank seal

Parts usually involved

  • Fuel cap
  • EVAP hoses
  • Vent valve
  • Charcoal canister

Test before you replace

Inspect the cap seal, then smoke test carefully since a very small leak can be hard to see.

General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.

Run your jobs from your phone
Show the customer the problem and get their yes in seconds.
Sign up free