OBD-II · Engine and powertrain (P)
P0456
EVAP system very small leak detected
What it means
The evaporative emission system has a very small leak, often a fuel cap seal or a tiny crack in a hose. Only cars with a leak-detection pump or tank pressure sensor run this test; many European-market cars do not.
Symptoms
- engine warning light
- no change in how the car drives
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | worn fuel cap seal |
| 02 | small crack in an EVAP hose or seal |
| 03 | leaking canister or purge valve |
| 04 | faulty leak-detection pump |
What to check, step by step
- 01Check the fuel cap: seal present, undamaged and tightened until it clicks
- 02Inspect the EVAP hoses, canister and filler neck for cracks and loose connections
- 03Smoke-test the EVAP system to find the leak
- 04Check the leak-detection pump or tank pressure sensor and the canister vent