The Mercedes-Benz S430 front side marker uses a 12961 bulb size, while the rear side marker requires a P21/4W or 12821 bulb size. The replacement chart covers vehicle production years spanning 2000 to 2006 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz S430 uses two distinct bulb types across its front and rear side marker positions, with the front position using a single bulb type across all model years in the specifications while the rear position uses two different bulb types depending on the year.
The front side marker on the S430 uses the 12961 bulb across the full 2000-2006 model year range covered in the specifications.
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 rear side marker on the S430 transitions from the 12821 bulb in 2000-2002 to the P21/4W bulb in 2003-2006, indicating a change in rear marker lamp hardware at that point in the production run.
The 12821 is also a Philips part number for a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W, sharing the same base type and electrical ratings as the 12961.
Despite sharing the same base type and ratings, the 12961 and 12821 carry different Philips part numbers and are specified for different positions on the vehicle, so cross-substitution between front and rear positions is not supported by the specifications.
The P21/4W is an ECE-standard dual-filament signalling bulb with a BAZ15d bayonet base, rated at 12V with filaments at 21W and 4W respectively.
The BAZ15d base of the P21/4W is mechanically and electrically incompatible with the W2.1x9.5d wedge base used by the 12821, meaning the two rear marker bulb types are not interchangeable across the 2000-2002 and 2003-2006 model years.
The dual-filament construction of the P21/4W, with its 21W and 4W outputs, represents a significantly different electrical load compared to the single 5W filament of the T10 wedge bulbs used in earlier rear marker and all front marker positions.
Correct year identification for the S430 is particularly relevant for the rear side marker position, where an incorrect bulb base type would prevent proper fitment entirely.