Kia Niro Tail Light Bulb Size

Additional Notes

• The 2357 bulb follows the ANSI standard used in the United States and Canada, while the P21/5W follows the ECE standard used in Europe and other international markets. Both share the BAY15d bayonet base, which is a two-pin offset base designed to prevent incorrect installation.
• The Kia Niro uses the 2357 bulb for its tail lights across the 2017-2020 model years. This bulb operates at 12V with a dual-filament output of 26.9W for the brighter stop function and 8W for the dimmer running light function.
• The 2357 is a brighter variant of the 1157 bulb. Although both share the BAY15d base and are physically interchangeable, the higher wattage of the 2357 produces greater light output, which is why fitment specifications distinguish between the two.
• The 2021-2022 Kia Niro tail lights use the P21/5W bulb, which operates at 12V with a dual-filament output of 21W and 5W. The lower wattage ratings of the P21/5W reflect the ECE standard's different output requirements compared to the ANSI-rated 2357.
• Despite the P21/5W and 2357 sharing the same BAY15d bayonet base, they are not confirmed interchangeable replacements for one another, as they originate from different regulatory standards with differing wattage outputs.
• The 2023-2024 Kia Niro tail lights use non-replaceable LED units, meaning the light source is integrated into the assembly and is not a serviceable bulb in the conventional sense.