Lexus RC F Courtesy Bulb Size

Additional Notes

• The Lexus RC F uses two distinct bulb sizes for its courtesy lighting across its model years: the 194 and the 168, both of which are ANSI-standardized miniature wedge bulbs of the T10 form factor rated at 12 volts.
• The 194 bulb is specified for the 2018-2019 and 2021-2022 model years, operating at 3.78 watts.
• The 168 bulb is specified for the 2015-2016 model years, operating at a higher wattage of 4.9 watts.
• Although the 194 and 168 share the same T10 wedge base and 12-volt rating, their wattage values differ, which means the two types are not electrically identical despite their physical interchangeability at the socket level.
• The T10 wedge base is a tubular single-filament design that seats without a bayonet or screw mechanism, relying instead on the tension of the socket contacts to retain the bulb.
• Both the 194 and 168 carry ANSI standardization applicable to the US and Canadian markets, meaning their electrical and physical characteristics conform to a defined industry specification rather than a proprietary one.
• The wattage difference between the 194 (3.78W) and the 168 (4.9W) reflects a difference in filament resistance, which affects the amount of current drawn from the vehicle's electrical circuit during operation.
• Substituting a 168 in place of a 194, or vice versa, in the Lexus RC F would result in a mismatch with the wattage specified for that model year's courtesy lighting circuit.