The Mercedes-Benz SL55 AMG front turn signal uses a 1156NA bulb size, while the rear turn signal requires either a 12496 or P21W bulb size. The replacement chart covers 2003 to 2008 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 1156NA bulb is the sole front turn signal bulb type across all listed model years of the Mercedes-Benz SL55 AMG, covering 2003-2008.
The 1156NA is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base and natural amber glass, making it the standard for North American markets.
The natural amber glass of the 1156NA produces amber light without relying on a colored lens, which is a defining characteristic of this bulb type in North American turn signal applications.
The rear turn signal specification for the SL55 AMG changed between the 2005 and 2006 model years, with 2003-2005 using the P21W and 2007-2008 using the 12496.
The P21W is an ECE-standard single-filament signalling bulb rated at 12V and 21W, also using a BA15s bayonet base, making it the international counterpart to the 1156NA in terms of base type and wattage.
Although the 1156NA and P21W share the same BA15s bayonet base and 12V/21W ratings, they are not interchangeable without consideration, as the 1156NA carries amber glass while the P21W uses clear glass intended for use with an amber lens.
The 12496 is a Philips/Osram part number designation for a 12V halogen bulb classified as a specialty application type, distinguishing it from the general-service P21W it replaced in the rear turn signal position.