P0456

Evaporative emission system very small leak detected.

The computer detected a very small seal loss in the fuel vapour system.

What should be checked

An opening, faulty seal or damage to the circuit may prevent the system from maintaining the test condition.

In plain language: Fuel vapours can escape through a lid, seal, hose or connection, but the point remains to be located.

How to check it: Visually check closures and accessible connections and use the authorised leak test afterwards.
Before correcting it: Don't declare a lid or a hose guilty without confirming where you're losing. The correction is decided only after locating and confirming the defect.
Related components: This path may involve the fuel cap, seals, hoses, connections, fuel tank, vapor canister, or filler neck. None has been confirmed.
When to stop: Do not use any improvised smoke, pressure or heat near fuel vapours.

Valves, circuits and pressure measurements are involved in the automatic testing of the evaporative system.

In plain language: The computer may not be opening, closing or measuring the vapor system properly.

How to check it: Check orders, response and seal with the appropriate diagram and tool.
Before correcting it: Don't apply current or change valves just for the code. The correction is decided only after locating and confirming the defect.
Related components: This path may involve purge or vent valves, the pressure sensor, leak-detection pump, connectors, or wiring. None has been confirmed.
When to stop: Tests with vapours or tank access must be carried out by trained persons.

Choose the make and open its official portal to find the manual, diagrams, cylinder arrangement, and bulletins for the exact vehicle.

Availability, registration, and cost depend on the manufacturer. The link does not grant permission to copy the manual.

Understand which emissions-related service information manufacturers must make available for purchase.

Explains regulated access in the United States; it does not contain the vehicle-specific diagram or make the manual free.

Audi A3 Quick Reference Specification Book — Audi of America / archivo NHTSA. It supports the punctual definition of the code; It does not identify a cause, a part or a repair.
Frequently Asked Questions About On-Board Diagnostics — U.S. Environmental Protection Agency. Supports the safety difference between a fixed breakdown lamp and a flashing lamp; It doesn't diagnose the cause.