The Mercedes-Benz C43 AMG brake light requires a P21W bulb size for the specific lighting components located at the rear of the vehicle. Data for the specified bulb covers the period from 1998 through 2000.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C43 AMG uses the P21W bulb for its standard brake lights across the 1998-2000 model years. This is an ECE-regulated single-filament signalling bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The center high mount stop light on the C43 AMG uses the H21W bulb for the same 1998-2000 model years. Like the P21W, it is an ECE-standard single-filament signalling bulb rated at 12V and 21W, but it uses a BAY9s base rather than a BA15s base.
The BA15s base of the P21W is a single-contact bayonet fitting, where the "15" refers to the 15mm base width. This base type is among the most widely used in automotive signalling applications.
The BAY9s base of the H21W is a single-contact bayonet fitting with offset pins, which physically prevents it from being interchanged with BA15s-based bulbs such as the P21W, despite both bulbs sharing the same 12V, 21W electrical rating.
Although the P21W and H21W share identical wattage and voltage ratings, their differing base types mean they are not interchangeable between the standard brake light and center high mount stop light positions on the C43 AMG.
Both the P21W and H21W carry ECE certification, indicating compliance with European and internationally adopted lighting regulations. This standard governs output, beam pattern, and safety requirements for signalling bulbs used in road vehicles.