Saturn Ion front and rear side marker bulbs require 168 and 3057 bulb sizes respectively, with the front utilizing the smaller size designation. The replacement chart covers 2003 through 2007 model years and documents bulb size specifications across the vehicle production range.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Saturn Ion uses two distinct bulb types across its side marker positions: the 168 for front locations and the 3057 for rear locations, with both specifications remaining unchanged across the 2003-2007 model years.
The 168 bulb is an ANSI-standardized miniature wedge type in a T10 form factor, rated at 12V and 4.9W, placing it among the lower-wattage bulbs commonly found in parking and marker applications.
The T10 wedge base of the 168 bulb is a widely used format in automotive lighting, where the bulb is held in place by the tension of the socket rather than a bayonet or screw mechanism.
The 3057 bulb is an ANSI-standardized dual-filament wedge type in a T25 form factor, rated at 12V with a 27W main filament and a 7W secondary filament.
The dual-filament design of the 3057 allows a single bulb to serve two brightness levels within one housing, a characteristic that makes it suitable for rear positions where both steady marker illumination and brighter signaling functions may be required.
Both the 168 and 3057 bulbs conform to ANSI standards recognized in the United States and Canada, indicating standardized electrical and physical specifications across manufacturers.
The T25 form factor of the 3057 is physically larger than the T10 of the 168, and the two bulb types are not interchangeable due to differences in size, wattage, and filament configuration.
The consistent use of the same bulb sizes across all five model years of the Saturn Ion means that a single bulb specification applies to the entire production run of the vehicle for each marker position.