Mercedes-Benz Metris Back Up Light Bulb Size

The Mercedes-Benz Metris back up light utilizes a P21W bulb size for illumination during reverse maneuvers. Available data for the specified component covers the period from 2016 through 2023.

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
2016-2023	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 Mercedes-Benz Metris uses the P21W bulb for the back up light position across the 2016-2023 model years.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe's regulations governing automotive lighting, a standard widely adopted outside North America.
The P21W operates at 12 volts and 21 watts, which is the typical power rating for single-filament signalling applications such as reverse lights.
The bulb uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset to one side, distinguishing it from the dual-contact BA15d variant.
Because the P21W is a single-filament bulb, it serves one lighting function only, unlike dual-filament types that handle two functions such as braking and running light duties simultaneously.
The BA15s base is not interchangeable with the BAY15d or BAZ15d bases, which carry different pin configurations despite sharing a similar overall form factor.