The Hyundai Elantra Coupe brake light requires a 2357 bulb size for proper installation and function within the lighting assembly. Data for the specified vehicle covers the range from 2013 to 2014.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 2357 bulb follows the ANSI standard used in the United States and Canada. It is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with filaments drawing 26.9W and 8W respectively. The higher-wattage filament serves the brake function, while the lower-wattage filament handles the running light function.
The 2357 is a brighter variant of the 1157 bulb. Both share the BAY15d base, which means the 2357 is physically interchangeable with the 1157 in many applications, though the higher wattage of the 2357 produces greater light output.
The P21W follows the ECE standard used in Europe and worldwide markets. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W. Because it carries only one filament, it serves a single lighting function rather than a combined stop and tail role.
The BA15s base of the P21W and the BAY15d base of the 2357 are not interchangeable. The BAY15d base has two offset pins to prevent incorrect installation of a dual-filament bulb, while the BA15s base has a single contact and two symmetrical pins.
The Hyundai Elantra Coupe uses the 2357 for the brake light position across the 2013-2014 model years, with the 2014 model carrying a fitment note specifying this size applies to vehicles without projector-type headlamps.
The P21W is specified for the Center High Mount Stop Light position across the 2013-2014 model years. This position requires only a single-filament bulb because it serves exclusively as a stop light with no combined running light function.
The two bulb types used across these positions represent different international standards and are not cross-compatible due to differences in base design, filament count, and wattage ratings.