The Mercedes-Benz C230 front side marker bulb uses 12961 or 2357NA size, while the rear side marker bulb uses 12821 size. The replacement chart covers 1997 to 2007 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 C230 front side marker position uses two distinct bulb types across its model years, with the 2002-2007 range specifying the 12961 and the 1997-2000 range specifying the 2357NA.
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 W2.1x9.5d base is a wedge-type connection, meaning the bulb is held in place by tension from the socket rather than by a locking bayonet mechanism.
The 2357NA follows the ANSI standard used in the United States and Canada. It is a dual-filament bulb with a BAY15d bayonet base and natural amber-tinted glass, rated at 12V with filaments drawing 26.9W and 8W respectively.
The dual-filament design of the 2357NA allows it to serve two lighting functions from a single housing, with the higher-wattage filament typically assigned to the brighter function.
The natural amber glass of the 2357NA produces an amber output without relying on a colored lens, which is a characteristic relevant to compliance with North American side marker regulations of that era.
The BAY15d bayonet base of the 2357NA is physically and electrically incompatible with the W2.1x9.5d wedge base of the 12961, making the two front side marker bulb types non-interchangeable across the C230 model year split.
The rear side marker position of the C230 uses the 12821 across all listed model years from 1997-2007, without the split seen at the front.
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 as the 12961 used at the front on 2002-2007 models.
Although the 12821 and 12961 share the same base type and electrical ratings, they carry different Philips part numbers, indicating a potential difference in physical size or optical output that warrants treating them as separate specifications.