Mercedes-Benz G550 4x4 front fog light uses H11 bulb size and rear fog light uses P21W bulb size. The replacement chart covers 2017 to 2018 production years with 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 G550 4x4 uses two distinct bulb types across its fog light positions: the H11 for the front fog lights and the P21W for the rear fog lights, covering the 2017-2018 model years.
The H11 is a single-filament halogen bulb rated at 12V and 55W, fitted with a PGJ19-2 base. Its higher wattage relative to the P21W reflects its role in forward illumination rather than signalling.
The P21W is a single-filament signalling bulb rated at 12V and 21W. Its lower wattage is consistent with rear fog light applications, where output requirements are less demanding than forward-facing lighting.
Both the H11 and P21W conform to ECE standards, meaning they are approved for use in Europe and worldwide. The H11 carries additional approval for use in the United States.
The H11 uses a PGJ19-2 base, while the P21W uses a BA15s bayonet base. These two base types are physically incompatible with each other, and substitution between the front and rear positions is not possible.
The BA15s designation on the P21W indicates a single-contact bayonet cap with a 15mm collar. This base type is common across many signalling and tail light applications, though wattage and voltage ratings must still match the vehicle specification before any replacement is considered.
The H11 belongs to a family of PGJ19-base halogen bulbs that includes similar types such as the H8 and H9. Despite sharing a physically compatible base in some cases, these variants differ in wattage and are not rated as interchangeable for the G550 4x4 front fog light position.