Mercedes-Benz 260E front turn signal bulbs use P21/5W size while rear turn signal bulbs use P21W size. The replacement chart covers 1987 to 1989 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz 260E uses two distinct bulb types across its turn signal positions: P21/5W for the front and P21W for the rear, across the 1987-1989 model years.
Both bulb types conform to the ECE standard, which governs lighting equipment regulations in Europe and numerous other markets worldwide.
The P21/5W is a dual-filament bulb, meaning it contains two separate filaments within a single globe, allowing it to serve more than one lighting function simultaneously.
The P21/5W operates at 12 volts and carries a wattage rating of 21W on its primary filament and 5W on its secondary filament, reflecting its dual-function design.
The P21W is a single-filament bulb rated at 12 volts and 21W, dedicated solely to its signalling role without a secondary lighting function.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The offset pin arrangement prevents the bulb from being seated in the wrong rotational position.
The P21W uses a BA15s bayonet base, a single-pin fitting. Because the P21W and P21/5W use different base types, the two bulbs are not interchangeable with each other.
The non-interchangeability of the BAY15d and BA15s bases is a relevant fitment consideration for the 260E, as both base types share a 15mm bayonet collar width but differ in pin configuration.