The Geo Storm front side marker uses a 168 or 194 bulb size, while the rear side marker requires a 194 bulb size. The replacement chart covers vehicle production spanning 1990 to 1993.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Geo Storm uses two bulb types across its side marker positions: the 168 and the 194. Both are ANSI-standardized miniature wedge bulbs of the T10 form factor, rated at 12 volts.
The 194 bulb draws 3.78 watts, while the 168 draws 4.9 watts. Although both share the same T10 wedge base and physical form factor, the wattage difference means they are not electrically identical.
The rear side marker position on the Geo Storm uses the 194 bulb across all model years covered, spanning 1990-1993.
The front side marker position on the Geo Storm uses the 194 bulb for the 1990-1992 model years.
For the 1993 model year, the Geo Storm front side marker specification changes to the 168 bulb, which differs from the 194 used in prior years despite sharing the same T10 base type.
Because the 168 and 194 share a T10 wedge base, physical installation of either bulb into the same socket is possible, but substituting one for the other would result in a wattage mismatch relative to the original specification.
The T10 wedge base design used by both bulb types requires no separate bulb holder or bayonet fitting, as the base contacts are formed directly into the glass envelope's wedge-shaped end.