Volkswagen ID.4 Turn Signal Bulb Size

Volkswagen ID.4 front turn signal uses a PY21W bulb size for replacement. The chart covers 2023 to 2024 production years with corresponding bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Front Turn Signal

Years	Bulb Size
2023-2024	PY21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament amber bulb with BAU15s bayonet base. 12V, 21W.	PY21W

Additional Notes

The PY21W is an ECE-standard single-filament amber bulb rated at 12 volts and 21 watts, fitted with a BAU15s bayonet base. The amber glass envelope is part of the bulb's construction, meaning the lens housing does not need to filter the light to produce the required turn signal color.
The BAU15s base uses an offset pin configuration, which physically prevents installation of non-amber bulb types sharing the same wattage and voltage rating, such as the P21W, whose BA15s base has symmetrically placed pins. This offset is a deliberate fitment control built into the ECE standard.
The Volkswagen ID.4 uses the PY21W for its front turn signal across the 2023-2024 model years.
At 21 watts, the PY21W draws a defined load on the vehicle's turn signal circuit. Replacing it with an LED unit that draws significantly less current can cause hyperflashing or a burnt-out bulb warning, unless the vehicle's flasher relay or load resistors are adjusted accordingly.