The Lexus RX350L back up light requires a bulb size of 921 for the specific lighting component located at the rear of the vehicle. Data for the bulb size covers the range from 2018 to 2021.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 921 is the sole bulb size listed across all back up light positions for the Lexus RX350L, covering both the standard and inner back up light assemblies.
The 921 bulb follows the ANSI standard used in the United States and Canada, meaning it conforms to a defined set of electrical and physical specifications recognized across North American markets.
It is a wedge-type bulb, classified under the T15 designation. The wedge base design means the bulb is held in place by the tension of the socket itself rather than by a bayonet or screw mechanism.
The 921 operates at 12 volts and draws 16 watts, which is consistent with standard automotive reverse light applications.
For the 2018-2019 Lexus RX350L, the inner back up light position also uses the 921 bulb, matching the outer position for those model years.
The 2018 inner back up light fitment carries a production date qualifier of "From 12/2017," indicating the specification applies only to vehicles produced from December 2017 onward within that model year.
The 2021 model year listing covers only the standard back up light position with the 921 bulb, without a separate inner back up light entry.