Maserati Quattroporte front and rear turn signal bulbs utilize H21W and 1156 bulb sizes respectively. The replacement chart covers vehicle production spanning 1984 to 2008.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H21W and 1156 bulb types are the two bulb sizes specified across all listed Maserati Quattroporte turn signal positions and model years.
Both the H21W and 1156 are single-filament, 12-volt, 21-watt bulbs, meaning they share identical electrical characteristics despite originating from different standardization systems.
The H21W follows the ECE standard, which governs automotive lighting in Europe and much of the world, while the 1156 follows the ANSI standard used in the United States and Canada.
Although the two bulb types are electrically equivalent, they are not interchangeable due to different base designs. The H21W uses a BAY9s base, and the 1156 uses a BA15s bayonet base.
The Maserati Quattroporte (2004-2008) front turn signal position uses the H21W bulb exclusively across all five listed model years.
The 1984-1986 Quattroporte uses the 1156 bulb for the front turn signal, reflecting the ANSI-standard fitment associated with North American market vehicles of that era.
The rear turn signal position is specified only for the 1984-1986 model years, all of which use the 1156 bulb.
The BAY9s base of the H21W is an offset bayonet fitting, which physically prevents substitution with the BA15s-based 1156 even though wattage and voltage ratings are identical.