Mercedes-Benz C300 front fog light bulbs utilize H7 and H11 sizes, while rear fog light bulbs use P21W size. The replacement chart covers 2008 through 2011 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 Mercedes-Benz C300 front fog light uses two different bulb sizes depending on the model year, with the 2010 model year requiring an H7 bulb and the 2008-2009 model years requiring an H11 bulb. These two types are not interchangeable due to their different base designs.
The H7 bulb follows the ECE standard and operates on a single-filament halogen design with a PX26d base, rated at 12V and 55W. It holds approval in Europe, worldwide markets, the United States, and Japan.
The H11 bulb also follows the ECE standard and uses a single-filament halogen design, though it features a PGJ19-2 base rather than the PX26d found on the H7. It is rated at 12V and 55W and carries approval in Europe, worldwide markets, and the United States, but not Japan.
Although the H7 and H11 share the same voltage and wattage ratings of 12V and 55W, their base types differ entirely, meaning one cannot substitute for the other in the C300 front fog light housing.
The rear fog light on the Mercedes-Benz C300 uses the P21W bulb across the 2008-2011 model years, making it consistent across that range.
The P21W is a single-filament signalling bulb rated at 12V and 21W, operating at a significantly lower wattage than the H7 and H11 halogen bulbs used in the front fog lights. It uses a BA15s bayonet base and conforms to the ECE standard.
The BA15s bayonet base of the P21W is a single-contact design, which is a defining fitment characteristic that distinguishes it from the pin-type bases used on the H7 and H11 halogen bulbs.