The Mercedes-Benz 380SE 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 1984 to 1985 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 380SE uses two distinct ECE-standard bulb types across its front and rear turn signal positions for the 1984-1985 model years.
The P21/5W is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base features offset pins, a design that prevents incorrect insertion and distinguishes it from single-filament bayonet bases.
The P21W is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base, which uses a single contact at the base tip.
The front turn signal position on the 380SE uses the P21/5W for both 1984 and 1985, while the rear turn signal position uses the P21W across the same years.
The P21/5W and P21W are not interchangeable despite sharing a similar wattage rating on their primary filaments, as their base types differ between BAY15d and BA15s respectively.
Both bulb types conform to ECE regulations, a standard recognized across Europe and numerous other markets worldwide.
The dual-filament design of the P21/5W allows a single bulb to serve two lighting functions simultaneously, which is typical in front positions where a parking or daytime running function accompanies the turn signal.