The Vespa GTS high beam and low beam headlight bulb size specifications both utilize a 9003 bulb size. The replacement chart covers vehicle production spanning 2009 to 2018.
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 bulb type listed across all headlight positions in the Vespa GTS specifications, covering both high beam and low beam functions for the 2009-2018 model years.
The 9003 is a dual-filament halogen bulb, meaning a single bulb contains two separate filaments: one rated at 60W for high beam output and one rated at 55W for low beam output.
The 9003 operates on a 12-volt electrical system, which is standard for most motor vehicles and scooters in this class.
The 9003 uses a P43t base, a bayonet-style mount with a 43mm flange width, which physically determines whether a bulb will seat correctly in a given housing.
The 9003 is an ANSI-designated standard recognized in the United States and Canada, making it a widely available bulb type in North American markets.
Because the Vespa GTS uses the same 9003 bulb for both the high beam and low beam positions, a single replacement bulb type serves both functions rather than requiring two separate part numbers.
The 9003 is functionally equivalent to the European H4 bulb in terms of wattage and dual-filament design, though the two types differ in base configuration and are not directly interchangeable without an adapter.