Saturn Ion front turn signal bulbs use 5702AK or 4157NA size, while rear turn signal bulbs use 3057 size. Replacement chart data covers 2003 to 2007 production 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 Saturn Ion uses two distinct front turn signal bulbs across its production years: the 5702AK for 2003, 2005, and 2007, and the 4157NA for 2004 and 2006.
The 5702AK is a Sylvania-specific part number rather than an ANSI standard designation, representing a coated variant of the ANSI 3157 bulb with an amber outer coating applied to an otherwise clear bulb.
The 4157NA carries an ANSI standard designation recognized in both the United States and Canada, and its amber color comes from natural amber glass rather than an applied coating.
Both the 5702AK and 4157NA share the same T25 wedge base, dual-filament construction, and 12V/27W/7W electrical ratings, meaning they are functionally equivalent in output and fitment despite differing in how their amber color is produced.
The rear turn signal position on the Saturn Ion uses the 3057 bulb across all model years from 2003-2007, making it the only position with no year-to-year variation in this specification set.
The 3057 is an ANSI standard dual-filament T25 wedge bulb rated at 12V, 27W/7W, the same electrical profile shared by the 5702AK and 4157NA used at the front.
The 3057 does not carry an amber coating or amber glass, distinguishing it from the front turn signal bulbs despite sharing the same base type and wattage ratings.
Because the front position alternates between the 5702AK and 4157NA depending on the model year, the amber appearance of the front turn signal lens assembly on the Saturn Ion is achieved through the bulb itself rather than a colored lens on all applicable years.