The Mercedes-Benz SL500 front fog light requires a 9006 or H1 bulb size, while the rear fog light uses a P21/4W bulb size. The replacement chart covers vehicle production spanning 1994 to 2006.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H1 bulb is the most frequently specified type across the Mercedes-Benz SL500 fog light data, covering the front fog light position for model years 1994-2002.
The H1 follows the ECE standard used in Europe and worldwide, though it also carries approval in the US and Japan. It is a single-filament halogen bulb rated at 12V and 55W, fitted with a P14.5s base.
The 9006 replaces the H1 as the front fog light bulb for the Mercedes-Benz SL500 in model years 2003-2006, representing a change in the specified standard from ECE to ANSI.
The 9006 is an ANSI-standard bulb intended for the US and Canadian markets. It is also a single-filament halogen type rated at 12V and 55W, but it uses a P22d base rather than the P14.5s base of the H1.
Although the H1 and 9006 share the same voltage and wattage ratings, their bases are physically different and the two types are not interchangeable. Installing one in a socket designed for the other is not possible without modification.
The P21/4W is specified for the rear fog light position on the SL500 for model years 1995-2002. It differs fundamentally from the front fog light bulbs in both function and construction.
The P21/4W is a dual-filament signalling bulb operating at 12V with a split wattage rating of 21W and 4W across its two filaments. It uses a BAZ15d bayonet base, which is an offset-pin design that prevents incorrect installation.
The ECE-standard P21/4W is not interchangeable with the single-filament halogen types used in the front fog positions, as it serves a signalling role and operates on a different base type and wattage configuration.