The Lexus RX400h uses a 168 bulb size for the front side marker and a 194 bulb size for the rear side marker. The replacement chart covers 2006 to 2008 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 RX400h uses two distinct bulb sizes across its side marker positions for the 2006-2008 model years: size 168 at the front and size 194 at the rear.
Both the 168 and 194 are ANSI-standardized bulb designations recognized in the United States and Canada, meaning they conform to a defined set of electrical and physical standards rather than being proprietary specifications.
Both bulbs share the T10 miniature wedge form factor, which refers to a small, wedge-shaped base that seats directly into a socket without a separate metal base or bayonet pins.
Both bulbs operate at 12 volts, consistent with standard automotive electrical systems.
The 168 bulb, used in the front side marker position, is rated at 4.9 watts, while the 194 bulb, used in the rear, is rated at 3.78 watts, making the front position the higher-wattage application of the two.
Although the 168 and 194 share the same T10 wedge base and voltage rating, their wattage ratings differ, and the two sizes are not interchangeable across front and rear positions on the RX400h.