The Ducati Monster S4 headlight uses a 9003 bulb size for both high beam and low beam functions. The replacement chart covers vehicle production years spanning 2004 to 2007.
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 specified for the Ducati Monster S4 across all listed headlight positions and model years.
The 9003 bulb is a dual-filament halogen type, meaning a single bulb contains two separate filaments, one for high beam output and one for low beam output.
Because the 9003 bulb serves both filament functions within one unit, the Monster S4 uses the same physical bulb for both the high beam and low beam headlight positions across the 2004-2007 model years.
The 9003 standard is the international designation for what is marketed in North America as the HB2 bulb, and it is electrically and physically equivalent to the H4 bulb used widely in European and Asian markets.
The H4 and 9003 share the same three-pronged P43t base, which means bulbs sold under either designation are interchangeable in fitment, provided they meet the same wattage rating.
The standard wattage rating for a 9003 bulb is 60 watts on the high beam filament and 55 watts on the low beam filament, operating on a 12-volt electrical system.
Replacement bulbs for the Monster S4 headlight must conform to the dual-filament 9003 specification, as single-filament alternatives would not replicate the full functionality of the original fitment.