The Mercedes-Benz G55 AMG outer tail light and tail light utilize a P21/5W bulb size, with the tail light also referenced as 12821. The replacement chart covers vehicle production years spanning 2003 to 2011, detailing bulb size specifications across the model's manufacturing range.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21/5W is a dual-filament bulb operating at 12V with a 21W main filament and a 5W secondary filament. It uses a BAY15d bayonet base and follows the ECE standard used across European and worldwide markets.
The BAY15d base on the P21/5W features offset pins, a design that prevents incorrect insertion by ensuring the bulb can only be seated in one orientation.
The 12821 is a Philips part number for a miniature wedge-style T10 bulb with a W2.1x9.5d base, rated at 12V and 5W. It is a single-filament bulb used in low-load signalling positions.
The Mercedes-Benz G55 AMG outer tail light uses both the P21/5W and the 12821 across its model years, with each serving a distinct function within the same light assembly given their differing wattage and filament configurations.
The P21/5W and the 12821 are not interchangeable. They differ in base type, filament count, and wattage, making substitution between the two incompatible with the socket and electrical requirements of each position.
For the 2011 Mercedes-Benz G55 AMG, the outer tail light specification lists the P21/5W for both of its recorded entries, indicating that year uses the dual-filament bayonet bulb across the relevant positions.
The 12821 appears across model years 2003-2010 in the outer tail light specifications, representing the longer-running fitment within the listed data.
The W2.1x9.5d wedge base of the 12821 is a friction-fit design, held in place by the socket walls rather than a locking mechanism, which is standard for low-wattage auxiliary positions.