Mercedes-Benz GL320 Back Up Light Bulb Size

The Mercedes-Benz GL320 back up light uses a P21W bulb size for the reverse lighting assembly. The replacement chart covers 2007 to 2009 production years with corresponding bulb specifications.

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
2007-2009	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 sole back up light bulb type listed for the Mercedes-Benz GL320, covering the 2007-2009 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 at a time, which is consistent with its role as a back up light rather than a combined stop/tail application.
The P21W operates at 12 volts and consumes 21 watts, placing it in the standard signalling power range for automotive reverse lighting.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, distinguishing it from the dual-contact BA15d variant. These two base types are not interchangeable despite their similar physical profile.