Nissan Altima Turn Signal Bulb Size

Additional Notes

• The "NA" suffix present on many bulb types used in the Nissan Altima's turn signal positions denotes natural amber glass, meaning the amber color is built into the bulb's glass envelope rather than produced by a colored lens or housing.
• Dual-filament bulbs appear across multiple front turn signal positions in the Altima specifications. Types such as the 1157, 1157NA, 7443NA, 7444NA, 2357NA, and 3457NA each carry two filaments operating at different wattages, which allows a single bulb to serve both a running light function and a higher-intensity turn signal function simultaneously.
• The 7443NA and 7444NA are both T20 wedge-base dual-filament bulbs rated at 12V with a 21W/5W output. Despite their near-identical specifications, they are listed as distinct part numbers and are not confirmed as interchangeable within these specifications.
• The 1034NA is described as a variant of the 1157 and shares the BAY15d bayonet base along with a 12V, 21W/5W dual-filament rating. The BAY15d base features two offset pins, which physically prevents incorrect installation of single-filament bulbs that use the single-pin BA15s base.
• The rear turn signal position for the 2023 Nissan Altima uses the 7440, a single-filament T20 wedge bulb without the NA amber glass treatment, while the front position for the same year uses the 2357NA, a dual-filament BAY15d bulb with natural amber glass. The two positions are therefore neither functionally nor physically interchangeable.
• The 2456 festoon bulb, listed for several rear turn signal positions, differs structurally from the wedge and bayonet-base types used elsewhere in these specifications. Festoon bulbs make contact at each end of the bulb body rather than through a base, placing them in a separate fitment category entirely.
• T20 and T25 designations refer to the bulb body width in millimeters, with T20 bulbs measuring 20mm and T25 bulbs measuring 25mm across the body. Wedge bulbs of different T-ratings are not interchangeable even when their wattage and voltage ratings match.
• The 1156NA and 1156 types, listed for the Altima's front and rear turn signal positions in the 1993-1997 range, use the single-pin BA15s bayonet base and carry a single filament rated at 12V and 21W. The NA variant adds the natural amber glass coating, but both share the same base type and wattage.