The Saturn SC2 brake light utilizes 3157, 2458, and 2057 bulb sizes depending on the specific production period for the vehicle. Data for the bulb sizes covers the range from 1993 to 2002.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Saturn SC2 brake light circuit relies on two bulb types across its production run: the 2057 for 1993-2000 models and the 3157 for 2001-2002 models.
The 2057 is a dual-filament bulb with a BAY15d bayonet base, operating at 12V with filaments rated at 26.9W and 8W, where the higher-wattage filament serves the brake function and the lower serves the running light function.
The 3157 is also a dual-filament bulb, though it uses a T25 wedge base rather than a bayonet mount, operating at 12V with filaments rated at 27W and 7W.
Because the 2057 uses a BAY15d bayonet base and the 3157 uses a T25 wedge base, the two bulb types are not physically interchangeable despite serving the same brake light function on the Saturn SC2.
The 2057 is described as a brighter variant of the 1157, sharing the same BAY15d base type, which means an 1157 may physically fit the socket but would not match the exact wattage output of the 2057.
The center high mount stop light on the Saturn SC2 uses the 921 for 1997-2002 models, a single-filament T15 wedge bulb operating at 12V and 16W.
The 1995-1996 Saturn SC2 center high mount stop light uses the PC168, a miniature T10 wedge bulb designed for a printed circuit board twist-lock socket, which is a physically distinct mounting system from the standard wedge socket used by the 921.
The PC168 and 921 are not interchangeable, as the PC168 requires a printed circuit board twist-lock socket while the 921 fits a conventional wedge socket.