Mercedes-Benz G550 4x4 Back Up Light Bulb Size

The Mercedes-Benz G550 4x4 back up light requires a P21W bulb size for proper installation and function. Data for the specific component covers the range from 2017 to 2018.

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
2017-2018	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

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Additional Notes

The P21W is the specified back up light bulb for the Mercedes-Benz G550 4x4 across the 2017-2018 model years.
The P21W follows the ECE (Economic Commission for Europe) standard, a regulatory framework adopted across Europe and numerous other markets worldwide.
As a single-filament bulb, the P21W is dedicated to one lighting function, which in this application is the back up light.
The P21W operates at 12 volts and draws 21 watts, placing it in the mid-range of standard automotive signalling bulb wattages.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, a base type that is not interchangeable with dual-contact bayonet variants such as the BA15d or BAY15d despite their similar physical appearance.