The Mercedes-Benz C32 AMG tail light requires P21/5W and 12821 bulb sizes for the rear lighting assembly. Data for the specified lighting components covers the period from 2002 through 2004.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C32 AMG outer tail light uses three distinct bulb types across its 2002-2004 model years: P21/4W, P21/5W, and the Philips 12821.
The P21/4W is an ECE-standard dual-filament signalling bulb rated at 12V with a 21W primary filament and a 4W secondary filament, fitted with a BAZ15d bayonet base.
The P21/5W shares the same ECE standard and dual-filament design but carries a 21W/5W rating and uses a BAY15d bayonet base, making it physically incompatible with the P21/4W despite their similar naming.
The BAZ15d and BAY15d bases differ in pin offset geometry, meaning P21/4W and P21/5W bulbs are not interchangeable even though both are dual-filament bayonet types operating at 12V.
The Philips 12821 is a single-filament miniature wedge bulb in the T10 form factor, using a W2.1x9.5d wedge base rated at 12V and 5W, a fundamentally different construction from the bayonet-based P21 series.
For the 2002 C32 AMG outer tail light, one of the two bulb positions specifies the Philips 12821 rather than the P21/5W that appears in the same position for 2003-2004 models, indicating a mid-production specification change.
The P21/4W fitment is consistent across all three model years (2002-2004) for one of the outer tail light positions, while the adjacent position reflects the specification difference noted above for 2002.
Because the T10 wedge base of the 12821 and the BAY15d bayonet base of the P21/5W are mechanically incompatible, substituting one for the other in the 2002 model year position is not physically possible without modification.