Mercedes-Benz G55 AMG front and rear side marker bulbs utilize 3893 and 12821 bulb sizes respectively. The replacement chart contains bulb size specifications across 2003 to 2011 vehicle production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 3893 is the dominant bulb type across the side marker specifications for the Mercedes-Benz G55 AMG, appearing in both front and rear positions across the majority of model years covered.
The 3893 is an ANSI-standardized bulb rated at 12V and features a BAY15d bayonet base with dual filaments, classifying it as a specialty application component rather than a general-purpose miniature bulb.
A BAY15d base uses a two-pin bayonet mount with pins offset at different heights, which physically prevents incorrect single-filament bulbs from being seated in the socket.
The dual-filament construction of the 3893 means the bulb is capable of serving two independent lighting functions within a single housing, a design common in combination marker and stop light applications.
The front side marker position on the G55 AMG uses the 3893 consistently across all listed model years, spanning 2003-2011.
The rear side marker position uses the 3893 for 2003-2010 but shifts to the 12821 for the 2011 model year, representing a fitment difference between that year and all prior listed years.
The 12821 is a Philips part number designation for a T10 miniature wedge bulb rated at 12V and 5W, using a W2.1x9.5d wedge base rather than a bayonet mount.
The W2.1x9.5d wedge base of the 12821 is not mechanically compatible with the BAY15d bayonet socket used by the 3893, making the two bulbs non-interchangeable despite both operating at 12V.
The 12821 is a single-filament bulb by virtue of its 5W single-wattage rating and T10 wedge format, which contrasts with the dual-filament design of the 3893 used in the same rear marker position on earlier model years.
The rear side marker socket configuration on the 2011 G55 AMG is therefore physically and electrically distinct from that of the 2003-2010 models, requiring the correct bulb type to be matched to the specific model year before installation.