The Mercedes-Benz SLK350 front fog light uses H7 and 9006 bulb sizes, while the rear fog light requires a P21W bulb size. The replacement chart covers 2005 through 2011 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz SLK350 front fog light does not use a single bulb type across all model years. The H7 and 9006 types alternate across the 2005-2011 range, meaning the correct bulb depends strictly on the specific model year.
The H7 is an ECE-standard single-filament halogen bulb rated at 12V and 55W, fitted with a PX26d base. It is used in the SLK350 front fog lights for the 2005, 2006, 2008, and 2011 model years.
The 9006 is an ANSI-standard single-filament halogen bulb also rated at 12V and 55W, but fitted with a P22d base. It is used in the SLK350 front fog lights for the 2007, 2009, and 2010 model years.
Although the H7 and 9006 share the same voltage and wattage ratings, their bases differ. The H7 uses a PX26d base while the 9006 uses a P22d base, making the two types physically non-interchangeable despite their identical electrical ratings.
The rear fog light on the SLK350 uses the P21W bulb consistently across all model years from 2005-2011, unlike the front fog light position which varies by year.
The P21W is an ECE-standard single-filament signalling bulb rated at 12V and 21W. Its BA15s bayonet base distinguishes it mechanically from the halogen types used in the front fog position.
At 21W, the P21W operates at considerably lower wattage than the 55W halogen bulbs used in the front fog lights, reflecting its role as a signalling rather than an illumination bulb.
The H7 carries approval for use in the United States and Japan in addition to its primary ECE certification, giving it broader regulatory acceptance than a regionally specific standard would otherwise allow.