The Mercedes-Benz C230 brake light utilizes P21/5W and P21W bulb sizes for the rear lighting system. Data for the specified components covers the period from 1997 through 2007.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C230 brake light specifications reference three distinct bulb types across its model years: P21/5W, P21W, and H21W, all of which conform to ECE standards used in Europe and worldwide markets.
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 dual-filament design allows a single bulb to serve two lighting functions, commonly brake and tail light operation.
The P21W is a single-filament bulb rated at 12V, 21W, and uses a BA15s bayonet base. Unlike the P21/5W, it carries only one filament, making it unsuitable as a direct replacement in sockets designed for dual-filament operation.
The BAY15d base of the P21/5W and the BA15s base of the P21W are physically distinct. The BAY15d has offset pins to prevent incorrect installation, while the BA15s has symmetrical pins. These two bulb types are not interchangeable.
The Mercedes-Benz C230 used the P21W for brake lights across the 1997-2000 model years, while the P21/5W was specified for the 2003-2007 model years.
The H21W is a single-filament bulb rated at 12V, 21W, and uses a BAY9s base. The BAY9s is a smaller bayonet fitting compared to the BA15s and BAY15d bases found on the P21W and P21/5W, making cross-substitution between these types physically incompatible.
The H21W bulb was specified exclusively for the Center High Mount Stop Light on the C230 for the 1997-2000 model years, a position that is a separate, dedicated brake signal lamp mounted higher than the primary brake lights.
The 2002 model year C230 brake light specification lists the P21W, placing it alongside the 1997-2000 entries that share the same bulb type, while the surrounding 2003-2007 model years transitioned to the P21/5W.
Because the P21/5W uses a BAY15d base with offset locating pins, it is designed to fit only in sockets wired for dual-filament use. Installing a single-filament P21W into such a socket would result in only partial circuit functionality.
All three bulb types referenced in the C230 specifications operate at 12V, consistent with standard automotive electrical systems, and all carry ECE certification applicable to vehicles sold in regulated international markets.