The Lexus LS600h uses a 7440NA bulb size for the front turn signal and 7440 or 921 bulb sizes for the rear turn signal. The replacement chart covers 2008 to 2012 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 Lexus LS600h front turn signal uses the 7440NA bulb across the 2008-2012 model years.
The 7440NA is a single-filament T20 wedge bulb rated at 12V and 21W, distinguished by its natural amber-tinted glass, which produces an amber output without requiring an amber lens or reflector housing.
The 7440 shares the same T20 wedge base, 12V supply, and 21W rating as the 7440NA, but its glass is clear rather than amber-tinted.
Both the 7440NA and 7440 conform to ANSI standards applicable to the US and Canadian markets.
The rear turn signal of the Lexus LS600h uses the 7440 for the 2010-2012 model years and the 921 for the 2008-2009 model years, indicating a bulb change between the 2009 and 2010 model years for that position.
The 921 is a T15 wedge bulb rated at 12V and 16W, making it lower in wattage than the 7440 and 7440NA, and it also has a physically smaller base that is not interchangeable with the T20 socket used by those bulbs.
Because the 7440NA and 7440 share the same T20 base and electrical ratings, they are physically interchangeable, though substituting a clear 7440 where a 7440NA is specified may affect the amber color output if the housing does not provide its own amber filtering.
The front and rear turn signal positions on the 2010-2012 LS600h both use T20 wedge bulbs, though the front specifies the amber-glass 7440NA while the rear specifies the clear 7440.
The 921 bulb used in the 2008-2009 rear turn signal position is not a drop-in substitute for the 7440 or 7440NA due to the difference in base size between the T15 and T20 form factors.
All three bulb types listed in the specifications, the 7440NA, 7440, and 921, are ANSI-standardized, meaning their electrical and physical characteristics follow a defined industry specification rather than being proprietary to a single manufacturer.