Maserati Quattroporte front side marker bulbs use 12961 size while rear side marker bulbs use P21/5W size. The replacement chart covers vehicle production years spanning 2004 to 2013.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The front side marker position on the Maserati Quattroporte uses the 12961 bulb across the 2004-2013 model years.
The 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W.
The T10 wedge base is a push-fit design, meaning the bulb seats directly into a socket without rotation, which is a common fitment method for low-wattage marker applications.
The rear side marker position on the Maserati Quattroporte uses the P21/5W bulb across the 2009-2012 model years.
P21/5W is an ECE-standard designation used across European and worldwide markets, indicating a dual-filament bulb with a BAY15d offset bayonet base, rated at 12V with filaments at 21W and 5W.
The BAY15d base features two pins at different heights, which prevents incorrect insertion and ensures the correct filament is engaged for each function.
The front and rear side marker positions on the Quattroporte use entirely different bulb types, with incompatible bases, making the two positions non-interchangeable.
The 5W single-filament output of the 12961 contrasts with the dual-filament P21/5W, which serves two separate lighting functions from a single bulb housing through its two distinct wattage ratings.