The Mercedes-Benz S55 AMG front turn signal bulb size is 2357NA, while the rear turn signal bulb size is 12496 or PY21W. The replacement chart covers 2001 to 2006 model 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 the 2357NA bulb for the front turn signal across all model years from 2001-2006, making it the only front turn signal type specified for this vehicle.
The 2357NA is an ANSI-standard dual-filament bulb rated at 12V with a wattage split of 26.9W and 8W across its two filaments, housed in a natural amber glass envelope with a BAY15d bayonet base.
The BAY15d base features two offset pins at different heights, which physically prevents incorrect single-filament bulbs from seating in a dual-filament socket, serving as a built-in fitment safeguard.
The natural amber glass of the 2357NA produces amber light directly from the envelope rather than relying on a clear bulb behind an amber lens, which is a characteristic of the NA (Natural Amber) designation in the ANSI naming convention.
The rear turn signal of the S55 AMG used the PY21W bulb from 2001-2005, an ECE-standard single-filament amber bulb rated at 12V and 21W with a BAU15s bayonet base.
The BAU15s base uses two pins at the same height but offset at an angle of 150 degrees, distinguishing it from the BAY15d base used on the front turn signal bulb. These two bases are not interchangeable.
For the 2006 model year, the rear turn signal specification changed from the PY21W to the 12496, a Philips/Osram part number designating a halogen bulb for specialty applications rated at 12V.
Because the front turn signal uses a dual-filament 2357NA while the rear uses single-filament bulbs, the two positions serve different circuit functions and the bulbs are not interchangeable between front and rear sockets.
The PY21W follows ECE regulations, which are the prevailing standards in European and international markets, while the 2357NA follows ANSI standards used in North America, reflecting that different regional specifications may appear within the same vehicle model.