Home › Fault Codes › Cars & OBD › Standard › P0456
P0456

Evaporative emission system very small leak detected

The ECU has detected a very small leak in the sealed EVAP system.

What this code means

The ECU has detected a very small leak in the sealed EVAP system.

Possible causes

  • Fuel-cap seal leak
  • Small crack in EVAP hose
  • Minor canister leak
  • Purge or vent valve not sealing fully

Common symptoms

  • Check engine light
  • Usually no noticeable driveability issue

Checks to make

  1. Inspect fuel cap and seal
  2. Check accessible EVAP hoses
  3. Smoke-test the EVAP system if the leak is not visible

Safety

  • Do not replace parts from the code alone. Confirm the fault with live data, wiring checks and manufacturer procedures. Keep clear of hot or moving engine components.

Model notes

The code definition is generic; exact diagnostic thresholds, component locations and repair procedures vary by vehicle.