The Volkswagen Jetta tail light utilizes P21W, 12821, P21/5W, and 232 bulb sizes depending on the specific vehicle configuration. Available data for the specified lighting components spans the range from 1980 through 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Volkswagen Jetta inner tail light positions on 2015-2018 models without LED tail lights use the 12961 bulb, a Philips miniature wedge type in the T10 form factor with a W2.1x9.5d base, rated at 12V and 5W.
The 12821 is also a Philips miniature wedge bulb in the T10 form factor with a W2.1x9.5d base, rated at 12V and 5W, making it technically equivalent to the 12961 despite carrying a different part number.
The outer tail light positions on 2015-2018 Volkswagen Jetta models without LED tail lights use the P21/5W, a dual-filament bulb with a BAY15d bayonet base rated at 12V, 21W/5W, conforming to ECE standards used in Europe and worldwide markets.
The BAY15d base of the P21/5W is an offset-pin bayonet fitting, which physically prevents it from being interchanged with single-filament P21W bulbs that use the BA15s base, even though both share the same general bayonet style.
The 1999 outer tail light position carries two separate fitment entries: P21/5W for standard production and 12821 for late model variants, indicating a mid-year specification change within that model year.
Outer tail light positions on 2006-2009 Jetta models use the P21W, a single-filament ECE-standard bulb with a BA15s bayonet base rated at 12V and 21W, which is distinct from the dual-filament P21/5W used in other model years.
The 1985 Volkswagen Jetta outer tail light uses the 232, an ANSI-standard festoon bulb with an SV8.5 base rated at 12V and 3W, a form factor that is physically incompatible with the wedge and bayonet types specified for all other model years.
Outer tail light positions on 1980-1984 and 1986-1992 Jetta models use the 12821 wedge bulb, while 1993-1999 models largely transition to the P21/5W dual-filament bayonet type, reflecting a shift in base technology across those generations.
The all-years condition "Without LED Tail Lights" on 2015-2018 entries indicates that Jetta trims equipped with factory LED tail lights do not use replaceable incandescent bulbs in those positions.
The P21/5W and P21W bulbs both follow ECE international standards, meaning their specifications are governed by a regulatory framework rather than a single manufacturer, unlike the 12961 and 12821 designations which are Philips-specific part numbers.