BMW 435i front turn signal bulb uses PY24WNA size while rear turn signal bulb uses P21W size. Replacement chart covers 2014 to 2016 model 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 BMW 435i uses two distinct bulb types across its front and rear turn signal positions for the 2014-2016 model years: the PY24WNA at the front and the P21W at the rear.
The PY24WNA is an ANSI-standard bulb intended for the US and Canadian markets. It operates at 12V and draws 24W, with an amber-tinted envelope and a PGU20-4 base.
The PGU20-4 base is a wedge-pin style base specific to the PY24WNA family, which means it is not interchangeable with bulbs using other base types such as bayonet or standard wedge fittings.
The PY24WNA is the amber variant of the ECE-standard PY24W. While the two share the same wattage and base type, the ANSI version carries the "NA" suffix to denote its North American compliance designation.
The front turn signal fitment of the BMW 435i with HID headlamps specifies the PY24WNA for all three model years covered, indicating this bulb is tied to the HID headlamp configuration rather than the vehicle year alone.
The P21W is an ECE-standard single-filament bulb rated at 12V and 21W. Its BA15s base is a single-contact bayonet fitting, which is among the most widely used bases in automotive signalling applications worldwide.
Because the P21W uses a BA15s bayonet base and the PY24WNA uses a PGU20-4 base, the front and rear turn signal bulbs on the 435i are physically incompatible with each other's sockets.
The P21W is a single-filament bulb, meaning it serves one lighting function per unit. It is not interchangeable with dual-filament variants such as the P21/5W, which shares the same envelope but uses a BA15d base with two contacts.