The 2006-2011 Chevrolet Impala has known issues with the EVAP system, a part of your emission control system.

The EVAP canister vent valve or valve solenoid wiring may fail causing illumination of the check engine light, setting code P0446, and problems filling the tank with fuel.

To correct the issue, the EVAP canister vent valve, solenoid, and wiring must be inspected. The most common fix is replacement of the wiring connector or replacement of the vent valve assembly.