Mercedes-Benz B Electric Drive Turn Signal Bulb Size
The Mercedes-Benz B Electric Drive front turn signal requires a 3457NA bulb size, while the rear turn signal uses either PY21W or 12496 bulb sizes. The replacement chart covers 2014 to 2015 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 Mercedes-Benz B Electric Drive uses the 3457NA bulb for the front turn signal across the 2014-2015 model years, specifically in vehicles equipped with halogen capsule headlamps.
The 3457NA is an ANSI-standard dual-filament wedge bulb in the T25 form factor, rated at 12V with a 27W/7W filament configuration and natural amber glass, making it compliant with US and Canadian lighting regulations.
The dual-filament design of the 3457NA allows a single bulb to serve two lighting functions at different wattage levels, which is a common arrangement in front signal positions that also handle parking or daytime running light duties.
The front turn signal fitment on the 2014-2015 B Electric Drive is conditional, applying only to the halogen capsule headlamp configuration, which indicates that other headlamp variants on the same vehicle may use a different bulb or no replaceable bulb at all.
The rear turn signal specification differs between the 2014 and 2015 B Electric Drive, with the 2014 model using the 12496 and the 2015 model using the PY21W.
The PY21W used in the 2015 rear turn signal is an ECE-standard single-filament amber bulb with a BAU15s bayonet base, rated at 12V and 21W, and is common in European-market vehicles.
The BAU15s base of the PY21W features an offset pin arrangement that prevents the bulb from being inserted in an incorrect orientation, distinguishing it from the more common BA15s base used in similar single-filament bulbs.
The 12496 used in the 2014 rear turn signal is a Philips/Osram part number designation for a 12V halogen bulb intended for specialty applications, meaning it is not identified by a universal ANSI or ECE type code.
The shift from the 12496 in 2014 to the PY21W in 2015 for the rear turn signal indicates that the two model years are not interchangeable in that position, and substituting one bulb for the other would be incorrect.
The 3457NA and PY21W operate on different international standards, ANSI and ECE respectively, and are not interchangeable despite both being amber single- or dual-filament 12V bulbs used in turn signal applications on the same vehicle.