The Lexus IS250 front and rear side marker bulbs both require a 194 size bulb for proper operation. The replacement chart covers vehicle production spanning 2006 to 2009 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 194 bulb is the sole bulb type specified for the Lexus IS250 across all side marker positions for the 2006-2009 model years.
The 194 bulb follows the ANSI standard recognized in both the United States and Canada, classifying it as a regionally standardized automotive component.
It belongs to the T10 miniature wedge form factor, a capless bulb type that seats directly into a wedge-style socket without requiring a separate base or bayonet fitting.
The 194 bulb operates at 12 volts with a power draw of 3.78 watts, placing it in the low-wattage range typical of marker and courtesy lighting applications.
The same bulb size, 194, is specified for both the front and rear side marker positions across all four model years covered, indicating a uniform fitment across the vehicle.
The T10 wedge format is a widely used standard, meaning the 194 bulb is physically interchangeable with other T10-based bulbs that share the same voltage and wattage ratings, though substitutions outside the 194 specification are not addressed in the provided data.