The BMW 740iL tail light utilizes P21/5W and 12821 bulb sizes for the rear lighting components. Data for the specified vehicle covers the range from 1993 through 2001.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 740iL outer tail light uses two distinct bulb types across its production years: the P21/5W and the 12821.
The P21/5W is an ECE-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. Its dual-filament design allows it to serve two lighting functions within a single housing.
The 12821 is a Philips-numbered miniature wedge bulb of the T10 type, rated at 12V and 5W, using a W2.1x9.5d base. As a single-filament wedge bulb, it serves a simpler, lower-wattage role than the P21/5W.
The BAY15d bayonet base of the P21/5W and the W2.1x9.5d wedge base of the 12821 are physically incompatible, meaning the two bulb types are not interchangeable with each other.
For the BMW 740iL outer tail light, the P21/5W fitment applies to model years 1995-2001 in one position grouping.
The 12821 fitment applies to model years 1993-1998 in a separate position grouping of the outer tail light.
Model years 1998-2001 carry P21/5W bulbs in one outer tail light position while simultaneously using different bulbs in another position, indicating that the outer tail light assembly on those vehicles contains more than one bulb socket.
The P21/5W is the dominant bulb type across the 740iL outer tail light specifications, appearing across all seven years of one position grouping and three years of another.