The Buick Encore GX turn signal requires a 7440 bulb size for the specific lighting component located on the exterior of the vehicle. Data for the bulb specifications covers the range from 2023 to 2024.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 7440 and 7440NA are both single-filament wedge bulbs built to the T20 form factor, operating at 12 volts and 21 watts under the ANSI standard applicable to the US and Canada.
The sole distinction between the 7440 and 7440NA is the glass envelope: the 7440NA uses natural amber-tinted glass, while the 7440 uses clear glass.
The Buick Encore GX rear turn signal takes the 7440 for the 2021, 2023, and 2024 model years.
The 2020 Encore GX rear turn signal specifies the 7440NA, which produces an amber output directly from the bulb rather than relying on a colored lens.
Because the 7440NA produces its amber color through the glass itself, substituting a clear 7440 in a socket designed for the 7440NA may alter the visible signal color at the lens.
Both bulb types share the same T20 wedge base, meaning they are physically interchangeable at the socket level, though the optical output differs between them.
The single-filament construction of both types means each bulb serves one lighting function only, with no secondary filament for a combined stop or running light role.