P0456 Very small leak in the fuel vapour (EVAP) system

Check this first

Try a new fuel cap before paying for a smoke test – it's the cheapest fix and often the right one.

What usually fixes it

In the order a good shop checks them. Typical total: $36–$395 at $130 an hour.

1. Fuel cap

   $36–$78

   Even a slightly worn seal sets this code.

2. EVAP hose or grommet

   $140–$315

   Tiny cracks that only show on a smoke test.

3. Purge valve

   $123–$330

   A valve that weeps when it should be shut.

Code titles are the generic SAE definitions. Prices are typical US parts and labor for a common car or light truck – a guide for judging a quote, not a quote. Always confirm a repair against the vehicle in front of you.