The Lexus IS350 front turn signal requires 7440NA, 7444NA, or 7443NA bulb sizes, while rear turn signal replacement uses 7440NA or 7440 bulb sizes. The chart covers 2006 through 2024 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 7440NA and 7440 are both single-filament T20 wedge bulbs rated at 12V and 21W. The key difference is that the 7440NA features natural amber glass, which produces an amber light output without requiring a colored lens or coating, while the 7440 uses clear glass.
The 7443NA and 7444NA are dual-filament T20 wedge bulbs, each rated at 12V with a 21W primary filament and a 5W secondary filament. The natural amber glass on both types serves the same function as on the 7440NA, producing amber output directly from the bulb.
All four bulb types across these specifications share the T20 wedge base form factor and operate on a 12V electrical system, which reflects the standard automotive electrical architecture used across these model years.
For the Lexus IS350, the front turn signal position uses dual-filament bulbs (7444NA or 7443NA) in the 2016-2019 and 2021 model years, while the 2022-2024 and 2006-2009 model years use the single-filament 7440NA in that same position.
The 7443NA and 7444NA are not interchangeable with the 7440NA or 7440 despite sharing the T20 wedge base, because the dual-filament types carry a second contact point to support the additional 5W filament circuit. Installing a single-filament bulb in a dual-filament socket would leave one circuit non-functional.
The rear turn signal position on the IS350 uses only single-filament bulbs across all listed model years, alternating between the 7440NA (amber glass) and the clear-glass 7440 depending on the specific year.
The 7443NA and 7444NA share identical wattage ratings (21W/5W) and the same T20 wedge base with natural amber glass. These two types differ in their internal pin configuration, which means they are not universally interchangeable despite their similar specifications.
All bulb types listed carry ANSI standardization applicable to the US and Canadian markets, indicating that the specifications reflect North American market fitment for the IS350.