Skip to content
Language: EN
Download

P0456: EVAP system very small leak detected

The seal test on the petrol vapour system finds a tiny leak. It is often the fuel cap seal, a porous hose or a valve not sealing fully.

Code P0456 at a glance
CodeP0456
SystemEngine and transmission
GroupP04xx, Emissions control
TypeGeneric: it means the same on every make
Can you keep driving?Yes, no rush

What P0456 means

The ECU checks whether the tank’s vapour circuit holds vacuum for a while. Here it loses it very slowly, which suggests a pinhole-sized leak. It is one of the hardest EVAP codes to track down.

Most common causes

  • Worn or cracked fuel cap seal
  • Non-original cap or one that does not fit properly
  • Porous vapour hose or one with a hairline crack
  • Vent or purge valve not sealing completely
  • Small leak at the canister or its joints

Symptoms

  • Engine warning light on
  • No change in how the car drives
  • Occasionally a faint smell of petrol

Can you drive with P0456?

Yes, no rush The car runs as normal and there is no immediate risk. It still needs fixing to pass inspection and stop vapour escaping.

How to check it

Replacing the fuel cap is the cheapest first step and cures many cases. If it persists, ask the garage for a smoke test, the reliable way to find leaks this small.

How to read and clear P0456 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0456 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0456 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Kia, Opel / Vauxhall, Toyota, Škoda. See what Final OBD does on your car in makes and models.

What does code P0456 mean?

The ECU checks whether the tank’s vapour circuit holds vacuum for a while. Here it loses it very slowly, which suggests a pinhole-sized leak. It is one of the hardest EVAP codes to track down.

Can you drive with P0456?

The car runs as normal and there is no immediate risk. It still needs fixing to pass inspection and stop vapour escaping.

How do you clear P0456?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0456 comes back.