The Mercedes-Benz 240D uses a P21/5W bulb size for front side marker applications and a 3893 bulb size for rear side marker positions. The replacement chart covers 1974 to 1983 model 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 240D front side marker position uses two distinct bulb types across its model years, with 1974-1976 models fitted with the 3893 and 1977-1983 models fitted with the P21/5W.
The rear side marker position uses the 3893 bulb across all listed model years, from 1974 through 1983, without variation.
The P21/5W is an ECE-standard bulb, meaning it was developed for European and worldwide markets rather than the North American regulatory framework.
The 3893 follows the ANSI standard, which governs bulb specifications in the United States and Canada.
Both the P21/5W and the 3893 are dual-filament bulbs, meaning each contains two separate filaments within a single envelope, typically serving two distinct lighting functions such as running light and turn signal.
Both bulb types share the BAY15d bayonet base, a two-pin offset base design where the two pins are positioned at different heights to prevent incorrect installation.
The P21/5W operates at 12V with a rated output of 21W on its primary filament and 5W on its secondary filament, reflecting its dual-filament configuration.
Although the P21/5W and the 3893 share the same BAY15d base type, their differing regulatory standards and wattage ratings mean they are not confirmed as interchangeable by these specifications.
The front side marker position on the 240D (Mercedes-Benz) is the only position in these specifications where a bulb type change occurs across model years.
The 3893 is classified as a specialty application bulb within the ANSI framework, distinguishing it from general-purpose automotive bulbs in that standard.