Mercedes-Benz C43 AMG Back Up Light Bulb Size

The Mercedes-Benz C43 AMG back up light utilizes bulb size 921 or P21W depending on the specific version of the vehicle. Data for the bulb sizes covers the range from 1998 through 2019.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2017-2019	921 (With Halogen Capsule Headlamps)
1998-2000	P21W

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Mercedes-Benz C43 AMG uses two distinct back up light bulb types across its model years: the 921 and the P21W, each governed by a different regional standard.
The 921 bulb follows the ANSI standard, which applies to the United States and Canada. It is a T15 wedge-base bulb rated at 12 volts and 16 watts.
The P21W bulb follows the ECE standard, used in Europe and worldwide markets. It is a single-filament signalling bulb with a BA15s bayonet base, rated at 12 volts and 21 watts.
The BA15s bayonet base of the P21W is not interchangeable with the wedge base of the 921, as the two bulbs use fundamentally different mounting systems.
Although both bulbs operate at 12 volts, the P21W draws 21 watts while the 921 draws 16 watts, meaning they are not equivalent in power consumption.
The 2017-2019 C43 AMG uses the 921 bulb size, with the specification applying specifically to vehicles equipped with Halogen Capsule Headlamps.
The 1998-2000 C43 AMG uses the P21W bulb size, reflecting the ECE regional standard associated with that generation.
The Halogen Capsule Headlamp qualifier on the 2017-2019 entries indicates that this fitment is conditional on a specific headlamp configuration, suggesting other headlamp variants on those model years may differ.