The Vespa S uses a 9003 bulb size for both high beam and low beam headlight applications. The replacement chart covers 2008 to 2014 model year data and specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9003 bulb is the sole headlight bulb type specified for the Vespa S across all listed model years, covering both high beam and low beam functions from 2008-2014.
The 9003 is a dual-filament halogen bulb, meaning a single bulb unit contains two separate filaments: one rated at 60W for high beam output and one rated at 55W for low beam output.
Because the 9003 serves both the high beam and low beam positions on the Vespa S, both headlight functions draw from the same physical bulb installed in the headlight housing.
The 9003 operates on a 12V electrical system and uses a P43t base, which is a bayonet-style fitting with a 43mm flange width that physically locks the bulb into the housing.
The 9003 is an ANSI-standardized bulb designation used in the United States and Canada. It is electrically and physically equivalent to the H4 bulb designation used in international markets, and the two are generally considered interchangeable.
The P43t base is a keyed fitting, meaning the bulb can only be seated in one orientation within the housing, which ensures the filaments align correctly with the reflector optics for proper beam projection.