From Ross-Tech Wiki
16840/P0456/001110 - EVAP System: Very Small Leak Detected
- Malfunction Indicator Light (MIL) active
- Fuel Cap not fully attached
- Evaporative Emission (EVAP) System leaking/faulty
- Check Fuel Cap
- Check Evaporative Emission (EVAP) System
- On 2006 and 2007 Passat, check fuel cap part number. Updated version ends in "G". Please refer to Technical Bulletin 2016757 for details.