The Kia K5 brake component utilizes 1157 and P21/5W bulb sizes according to the provided specifications for the lighting system. Data for the specific bulbs covers the range from 2021 to 2024.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Kia K5 uses the 1157 bulb for its brake lights across the 2021-2024 model years, making it the dominant bulb type in these specifications.
The 1157 is an ANSI-standardized dual-filament bulb operating at 12V with a 21W/5W output, meaning the higher wattage filament serves the brake function while the lower wattage filament handles a secondary role such as a tail light.
Its BAY15d bayonet base features two offset pins at different heights, a design that prevents incorrect insertion and ensures the two filaments connect to the correct circuits.
The Kia K5 (2021-2023) uses a separate 12961 bulb designated specifically for the inner brake position, indicating a split brake light assembly where the inner and outer sections draw from different bulb types.
The 12961 is a Philips part number for a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W, which is a significantly lower output than the 1157 used in the outer brake position.
The wedge base of the 12961 is physically incompatible with the BAY15d bayonet socket of the 1157, meaning the two bulb types are not interchangeable despite both operating on a 12V system.
The single-filament design of the 12961 contrasts with the dual-filament 1157, reflecting the different functional demands placed on the inner brake position versus the outer brake and tail light position.
The 1157 is produced by multiple manufacturers under the ANSI standard designation, while the 12961 is identified by a Philips-specific part number, which may affect cross-brand substitution when sourcing replacements.