The Mercedes-Benz 300SE uses a 1034 bulb size for front turn signals and P21W bulb size for rear turn signals. The replacement chart covers 1988 to 1993 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 300SE front turn signal uses two distinct bulb types across its model years: the 1034 for 1992-1993 and the P21/5W for 1988-1991.
The 1034 is an ANSI-standard dual-filament bulb rated at 12V with a 21W/5W output, fitted with a BAY15d bayonet base, and is classified as a variant of the 1157.
The P21/5W is an ECE-standard dual-filament bulb also rated at 12V with a 21W/5W output and shares the same BAY15d bayonet base as the 1034.
Although the 1034 and P21/5W share the BAY15d bayonet base and identical wattage ratings, they follow different regulatory standards, with the 1034 conforming to ANSI specifications used in the US and Canada and the P21/5W conforming to ECE specifications used in Europe and worldwide.
The rear turn signal on the 300SE uses the P21W across all listed model years from 1988-1993, making it the only rear turn signal bulb specified for this vehicle.
The P21W is an ECE-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The BA15s base of the P21W and the BAY15d base of both front turn signal bulbs are not interchangeable, as the BAY15d features offset locating pins to accommodate its dual-filament design, while the BA15s uses a single-filament configuration with symmetrical pins.