The Mercedes-Benz 280SE uses a P21/5W bulb size for the front turn signal and a P21W bulb size for the rear turn signal. The replacement chart covers vehicle production spanning 1968 to 1980.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz 280SE uses two distinct bulb types across its front and rear turn signal positions: the P21/5W for the front and the P21W for the rear, across all model years listed in the specifications.
Both the P21/5W and P21W are ECE-standard bulbs, meaning they conform to European and international regulations for signalling lamps and are not North American SAE-standard components.
The P21/5W is a dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The offset pins of the BAY15d base are positioned at different heights to prevent incorrect installation.
The P21W is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base. The BA15s base features two pins at the same height, distinguishing it physically from the BAY15d base used by the P21/5W.
Because the P21/5W and P21W use different bayonet base configurations, BAY15d and BA15s respectively, the two bulb types are not interchangeable with each other despite sharing the same 21W primary wattage rating.
The front turn signal position of the 280SE calls for the P21/5W across the 1968-1973 and 1977-1980 model years, indicating a consistent dual-filament front signalling requirement throughout the listed production span.
The rear turn signal position of the 280SE calls for the P21W across the same 1968-1973 and 1977-1980 model years, indicating a consistent single-filament rear signalling requirement throughout the listed production span.
The dual-filament nature of the P21/5W front turn signal bulb suggests the front position serves more than one lighting function, with the lower-wattage 5W filament typically associated with a parking or daytime running light role alongside the 21W turn signal filament.