The Mercedes-Benz C280 front turn signal uses bulb sizes 1156NA, 2357NA, or P21/5W, while the rear turn signal requires 12496 or P21W bulbs. The replacement chart covers 1994 through 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 2357NA bulb is the most frequently specified front turn signal bulb across the Mercedes-Benz C280 model years covered, appearing for the 1997-2000 model years as a single fitment and for 2006-2007 as the HID headlamp variant. It is a dual-filament ANSI-standard bulb rated at 12V with a high/low wattage of 26.9W/8W, mounted on a BAY15d bayonet base with natural amber glass.
The 1156NA shares the same BA15s bayonet base as the P21W but is a single-filament ANSI-standard bulb with natural amber glass, rated at 12V and 21W. Its ECE counterpart, the P21W, carries identical voltage and wattage ratings but follows the European ECE standard rather than the North American ANSI standard.
The P21/5W and 2357NA both use the BAY15d bayonet base, meaning the base type alone does not confirm interchangeability. The P21/5W is rated at 21W/5W under ECE standards, while the 2357NA is rated at 26.9W/8W under ANSI standards, representing a difference in filament output between the two.
For the 2006-2007 Mercedes-Benz C280 front turn signal, the correct bulb size depends on the headlamp type installed. Vehicles with halogen capsule headlamps take the 1156NA, a single-filament bulb, while vehicles with HID headlamps take the 2357NA, a dual-filament bulb. Substituting one for the other would result in a filament count mismatch.
The 12496 is identified by a Philips/Osram part number rather than an ANSI or ECE standard designation, classifying it as a specialty halogen bulb rated at 12V. It serves as the rear turn signal bulb for the C280 across the 1998-2000 and 2006-2007 model years.
The P21/5W, specified for the 1994-1996 front turn signal, uses the BAY15d offset-pin bayonet base. This offset pin design physically prevents incorrect single-filament bulbs from being seated in a dual-filament socket, as the pin positions differ from those of the BA15s base used on single-filament types.
The rear turn signal for the 1994-1997 C280 uses the P21W, an ECE-standard single-filament bulb on a BA15s bayonet base rated at 12V and 21W. Starting with the 1998 model year, the rear turn signal specification shifts to the 12496, a specialty halogen type, indicating a socket or housing change between those model years.