Mercedes-Benz GL450 front fog light uses an H11 bulb size, while rear fog light applications require either H21W or P21W bulb sizes. The replacement chart covers vehicle production spanning 2007 to 2016 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 GL450 front fog light uses the H11 bulb across all listed model years, specifically 2007-2011.
The H11 is a single-filament halogen bulb operating at 12V and 55W, fitted with a PGJ19-2 base. It conforms to ECE standards and carries approval for use in the United States as well as international markets.
The rear fog light position shows two distinct bulb types across the listed model years, with P21W fitted in 2007-2009 and H21W fitted in 2010-2016.
The P21W is a single-filament signalling bulb rated at 12V and 21W, using a BA15s bayonet base. It conforms to ECE standards for use in Europe and worldwide markets.
The H21W is also a single-filament signalling bulb rated at 12V and 21W, but it uses a BAY9s base rather than the BA15s base found on the P21W. Despite sharing the same voltage and wattage, the two bulbs are not interchangeable due to their differing base types.
The base difference between the P21W and H21W is a critical fitment consideration for the GL450 rear fog light. Installing a P21W in a socket designed for the H21W, or vice versa, is not physically compatible without modification.
The H11 front fog bulb at 55W draws significantly more power than either rear fog bulb at 21W, reflecting the functional difference between an illuminating fog light and a signalling fog light.
All three bulb types listed in these specifications, H11, H21W, and P21W, operate on a standard 12V automotive electrical system and conform to ECE regulations.