Lexus HS250h back up light bulbs utilize 921 and 3057 sizes for the outer and inner positions respectively. The replacement chart covers 2010 to 2012 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Lexus HS250h uses the 921 bulb for the standard back up light across the 2010-2012 model years.
The 921 is an ANSI-standard wedge bulb in the T15 form factor, rated at 12 volts and 16 watts.
The T15 designation refers to the bulb's tubular shape, with the number indicating its width in eighths of an inch, making it a relatively compact single-filament wedge type.
The inner back up light on the Lexus HS250h uses the 3057 bulb for the 2010-2011 model years and for 2012 production up to January 2012.
The 3057 is an ANSI-standard dual-filament wedge bulb in the T25 form factor, rated at 12 volts with a 27-watt high filament and a 7-watt low filament.
The dual-filament design of the 3057 serves two separate circuit functions within a single bulb housing, which distinguishes it from the single-filament 921 used in the standard back up position.
The 921 and 3057 are not interchangeable despite both being wedge-type bulbs, as they differ in filament count, wattage, and physical form factor.
Both the 921 and 3057 carry ANSI standardization for the US and Canadian markets, meaning their electrical and physical specifications conform to a defined industry standard rather than a proprietary one.