The Volkswagen 411 front turn signal uses a 1157 bulb size while the rear turn signal requires a P21W bulb size. The replacement chart covers 1971 to 1973 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.
The Volkswagen 411 uses two distinct turn signal bulb types across its front and rear positions for the 1971-1973 model years: the 1157 at the front and the P21W at the rear.
The 1157 is an ANSI-standard bulb used in the United States and Canada. It operates on 12 volts and carries a dual-filament design rated at 21W and 5W, mounted on a BAY15d bayonet base.
The dual-filament configuration of the 1157 allows it to serve two lighting functions from a single housing, with the higher-wattage filament typically handling the turn signal function and the lower-wattage filament serving a secondary role such as parking or running light.
The P21W follows the ECE standard used in Europe and worldwide. It is a single-filament bulb rated at 21W on a 12-volt circuit, fitted with a BA15s bayonet base.
The BAY15d base of the 1157 and the BA15s base of the P21W are not interchangeable. The BAY15d base features offset pins to accommodate its dual-filament design, while the BA15s base has a single contact and symmetrical pins suited to a single-filament bulb.
Because the 1157 and P21W share the same 21W rating on their primary filaments and both operate at 12 volts, their electrical output for signalling purposes is equivalent, though their physical bases differ.
The front turn signal position on the Volkswagen 411 calls for the 1157 across all three listed model years, 1971-1973, with no variation in specification during that period.
The rear turn signal position on the Volkswagen 411 calls for the P21W across all three listed model years, 1971-1973, with no variation in specification during that period.