BMW 440i front turn signal uses PY24WNA bulb size and rear turn signal uses P21W bulb size. Replacement chart covers 2017 to 2018 model years with bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 440i uses two distinct bulb types across its front and rear turn signal positions: PY24WNA for the front and P21W for the rear, both across the 2017-2018 model years.
The PY24WNA is an ANSI-standard bulb used in North American markets (the United States and Canada), functioning as the amber-colored variant of the ECE-standard PY24W.
The PY24WNA operates at 12 volts and 24 watts, and it uses a PGU20-4 base, which is a wedge-type locating base designed to ensure correct angular positioning of the amber bulb.
The front turn signal position on the BMW 440i specifies the PY24WNA exclusively for vehicles equipped with HID headlamps, indicating that this fitment is conditional on the headlamp type installed.
The P21W is an ECE-standard single-filament bulb used across European and worldwide markets, operating at 12 volts and 21 watts with a BA15s bayonet base.
The BA15s base on the P21W is a single-contact bayonet fitting, which is not interchangeable with dual-contact bayonet bases such as the BA15d, making base type a critical factor in fitment.
The PY24WNA and P21W operate at different wattages (24W and 21W respectively), meaning the two bulb types are not interchangeable with each other despite both being 12-volt single-filament signal bulbs.
The P21W serves the rear turn signal position on the 440i for both the 2017-2018 model years, with no conditional fitment qualifiers attached to this position.