Buick Regal Turn Signal Bulb Size

Additional Notes

• The 4157NA bulb is the most frequently specified front turn signal bulb across the Buick Regal's history, covering the 1997-2004 and 2011-2013 model years (with halogen capsule headlamps for 2012-2013), as well as 1997-2004. It is a dual-filament T25 wedge bulb rated at 12V and 27W/7W with natural amber glass.
• The 1157 and its NA-suffix variant share the same BAY15d bayonet base and 12V, 21W/5W dual-filament configuration. The NA suffix denotes natural amber-tinted glass, which produces the amber signal color without relying on a colored lens.
• For the 2014-2017 Buick Regal, the front turn signal bulb specification splits based on headlamp type. Vehicles with halogen capsule headlamps use the 7440NA, a single-filament T20 wedge bulb, while vehicles with HID headlamps use the 12188, a Philips specialty halogen bulb. These two bulbs are not interchangeable with each other.
• The 7440NA and 7440 share the same T20 wedge form factor and 12V, 21W rating. The 7440NA adds natural amber glass, making it the front-specific variant, while the clear 7440 is used at the rear for the same 2014-2017 model years.
• The 2057 and 2057NA are described as brighter variants of the 1157, both using the BAY15d bayonet base at 12V, 26.9W/8W versus the 1157's 21W/5W. The Regal used these bulbs in the front and rear turn signal positions during the 1983-1986 model years.
• The 3157 and 3057 are both dual-filament T25 wedge bulbs rated at 12V and 27W/7W. Despite sharing identical wattage ratings, they carry distinct ANSI designations and are not confirmed as interchangeable within these specifications.
• The 890 bulb, specified for the 1988-1990 Regal front turn signal, is a single-filament halogen bulb with a PG13 base rated at 12V and 27W. Its PG13 base type is physically distinct from the wedge and bayonet bases used in all other Regal turn signal positions, making it incompatible with those sockets.
• The 1034NA, used in the front turn signal position for the 1973-1974 and 1980 Regal, shares the BAY15d bayonet base with the 1157 family and carries the same 12V, 21W/5W dual-filament rating, though it carries a separate ANSI designation.
• The 3457NA, specified for the 2012-2013 Regal front turn signal on HID headlamp-equipped vehicles, shares the same T25 wedge form factor and 27W/7W rating as the 4157NA used on halogen headlamp variants of the same years. Both carry natural amber glass, but they hold distinct ANSI part numbers.
• Across the full specification range, the rear turn signal consistently uses clear-glass bulbs such as the 1157, 3057, 3157, 2057, and 7440, while the front turn signal positions predominantly specify NA-suffix (natural amber) variants of equivalent bulb types. Substituting a clear bulb for an NA-suffix bulb, or vice versa, would affect the color output at the lens.