The Chevrolet Cobalt brake light components utilize 3157 and 2458 bulb sizes for the lighting system. Data for the specific vehicle covers the range from 2005 to 2010.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Chevrolet Cobalt uses two distinct bulb types across its brake lighting system for the 2005-2010 model years: the 3157 for the standard brake lights and the 912 for the Center High Mount Stop Light.
The 3157 is a dual-filament bulb, meaning it serves two separate lighting functions within a single unit. Its filaments operate at 27W for the brake/stop function and 7W for the lower-intensity parking or tail light function.
The 3157 follows the T25 wedge form factor and is rated at 12 volts, conforming to ANSI standards recognized in both the United States and Canada.
The 912 is a single-filament wedge bulb in the T15 form factor, rated at 12 volts and 12 watts, also carrying ANSI certification for the US and Canadian markets.
The 912 is a variant of the 921 bulb. While the two share the same T15 wedge base and 12-volt rating, they differ in wattage, with the 921 typically rated at 16.8W. Substituting a 921 for a 912 in the Center High Mount Stop Light position introduces a higher wattage than the original specification.
Because the 3157 is a dual-filament bulb and the 912 is a single-filament bulb, the two types are not interchangeable with each other, nor do their wedge base sizes match.