The BMW M235i uses a 12496 PY21W bulb size for front turn signals and P21W for rear turn signals. Replacement chart data covers 2014 through 2016 model 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.
The PY21W is an ECE-standard single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s bayonet base. The amber color is built into the bulb itself rather than the lens.
The P21W shares the same 12V, 21W rating as the PY21W but uses a BA15s bayonet base instead of a BAU15s. These two base types are not interchangeable despite their similar appearance.
The BAU15s base on the PY21W has offset pins, while the BA15s base on the P21W has straight pins. This physical difference prevents incorrect installation between the two types.
The 12496 is a Philips/Osram part number designating a halogen bulb for specialty applications, rated at 12V. It is a manufacturer-specific designation rather than a universal ECE standard code.
The BMW M235i front turn signal uses the 12496 bulb for the 2015-2016 model years, while the 2014 model year uses the PY21W. These two bulbs serve the same position but are not listed as interchangeable.
The rear turn signal on the BMW M235i uses the P21W across all three model years covered, spanning 2014-2016.
Both the PY21W and P21W are governed by ECE regulations, which are applied across European and worldwide markets. This standard defines the electrical and photometric requirements each bulb must meet.
The front and rear turn signal positions on the M235i use different bulb types. The rear position standardizes on the P21W, while the front position varies by model year between the PY21W and the 12496.