BMW 430i Gran Coupe front turn signal uses PY24WNA bulb size and rear turn signal uses P21W bulb size. The replacement chart covers 2017 to 2018 vehicle production years with bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 430i Gran Coupe uses two distinct bulb types across its front and rear turn signal positions: PY24WNA for the front and P21W for the rear, a split that applies to both the 2017-2018 model years covered in the specifications.
The PY24WNA is an ANSI-standard bulb intended for the US and Canadian markets. It operates at 12V and draws 24W, making it slightly more powerful than its rear counterpart.
The PY24WNA is the amber variant of the ECE-standard PY24W and uses a PGU20-4 base. The PGU20-4 is a wedge-type base with offset pins, which physically prevents substitution with bulbs using incompatible bases.
The front turn signal fitment of PY24WNA on the 2017-2018 BMW 430i Gran Coupe applies specifically to vehicles equipped with HID headlamps, meaning this bulb size is conditional on that headlamp configuration.
The P21W is an ECE-standard bulb recognized across European and worldwide markets. It operates at 12V and draws 21W, functioning as a single-filament signalling bulb.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting. This base type is common in signalling applications but is not interchangeable with dual-contact BA15d bases used in some other automotive bulbs.
The rear turn signal position on the 2017-2018 430i Gran Coupe uses the ECE-standard P21W, while the front uses the ANSI-standard PY24WNA, reflecting a mixed regulatory standard across positions on the same vehicle.