BMW M240i front turn signal uses 12496 bulb size while rear turn signal requires 7440 or P21W bulb size for replacement. The chart covers 2017 to 2020 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.
The BMW M240i front turn signal uses the 12496 bulb for the 2017-2018 model years. This designation is a Philips/Osram part number rather than a universal industry standard, indicating a specialty halogen application operating at 12V.
The 12496 is not defined by ANSI or ECE standards, meaning it is sourced through manufacturer-specific channels rather than general automotive bulb catalogs.
The BMW M240i rear turn signal uses two different bulb types depending on the model year. The 2017-2018 model years use the P21W, while the 2019-2020 model years use the 7440.
The P21W and 7440 share identical electrical ratings of 12V and 21W and are both single-filament bulbs, but they are not interchangeable due to different base types. The P21W uses a BA15s bayonet base, while the 7440 uses a T20 wedge base.
The P21W follows the ECE standard, which is the regulatory framework used in Europe and many other markets worldwide. Its BA15s bayonet base requires a twist-and-lock socket.
The 7440 follows the ANSI standard, which governs bulb specifications in the United States and Canada. Its T20 wedge base is inserted directly into a friction-fit socket without rotation.
The rear turn signal socket type on the BMW M240i differs between the 2017-2018 and 2019-2020 model years, reflecting the change from a bayonet-style fitting to a wedge-style fitting.