The Mercedes-Benz S55 AMG front side marker uses a 12961 bulb size, while the rear side marker requires a P21/4W bulb with 12821 designation. The replacement chart covers 2001 to 2006 model production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz S55 AMG uses two distinct bulb types across its front and rear side marker positions, with the front position using a miniature wedge format and the rear position using either a wedge or dual-filament bayonet format depending on the model year.
The front side marker on the S55 AMG uses the 12961 bulb across all listed years, 2001-2006. This is a Philips miniature wedge bulb in the T10 form factor, rated at 12V and 5W, with a W2.1x9.5d base.
The T10 wedge base designation refers to a single-contact, wedge-shaped base that is held in place by tension rather than a locking mechanism, which is a common format in low-wattage automotive marker and interior lighting applications.
The rear side marker on the S55 AMG uses the P21/4W bulb for model years 2003-2006. This bulb follows the ECE standard used in European and worldwide markets, operates at 12V, and carries a dual-filament rating of 21W and 4W.
The P21/4W uses a BAZ15d bayonet base, which is an offset single-contact bayonet design. The offset pin placement prevents incorrect installation of a single-filament bulb in a socket intended for dual-filament operation.
For the 2001-2002 S55 AMG, the rear side marker uses the 12821 bulb instead of the P21/4W. The 12821 is a Philips miniature wedge bulb in the T10 form factor with a W2.1x9.5d base, rated at 12V and 5W.
The 12961 and 12821 share the same base type, voltage, wattage, and form factor, both being T10 wedge bulbs with W2.1x9.5d bases at 12V and 5W, though they carry different Philips part numbers.
The rear side marker position on the S55 AMG is not interchangeable across all model years, as the 2001-2002 fitment calls for a 5W T10 wedge bulb while the 2003-2006 fitment requires a dual-filament 21W/4W bayonet bulb, representing a difference in both socket type and wattage.