Volkswagen Cabriolet Back Up Light Bulb Size

The Volkswagen Cabriolet back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Available data covers the specific time range from 1985 through 1993.

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
1985-1993	P21W

Bulb Specifications

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

Other Locations

Additional Notes

The Volkswagen Cabriolet uses the P21W bulb for its back up light across the 1985-1993 model years.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe's regulations, which govern lighting equipment used in European and international automotive markets.
This bulb operates on a 12-volt electrical system and draws 21 watts, which is typical for single-filament incandescent signalling applications.
The P21W carries a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single contact at the base, distinguishing it from dual-contact variants.
Because the P21W is a single-filament bulb, it serves one lighting function only, which in this fitment is the reverse light.
The BA15s base type is not interchangeable with the BA15d base, which carries two contacts. Substituting a dual-contact bulb in a single-contact socket is not compatible with this application.
The P21W designation is also cross-referenced in some markets as the 1156 bulb, though the 1156 is an SAE standard type and minor electrical differences between the two standards exist depending on the manufacturer.