Mercedes-Benz CLA45 AMG front and rear turn signal bulbs use PY21W or 12496 sizes as replacement options. The chart covers 2014 to 2020 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 CLA45 AMG uses three distinct front and rear turn signal bulb types across its 2014-2020 model years: the PY21W, the 12496, and the 3457NA.
The 3457NA is an ANSI-standard dual-filament bulb rated at 12V with a 27W main filament and a 7W secondary filament. Its natural amber glass produces the required amber signal color without relying on a tinted lens or housing.
The PY21W is an ECE-standard single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s bayonet base. The offset pin arrangement of the BAU15s base is specific to amber signal applications and is not interchangeable with the standard BA15s base used on clear single-filament bulbs.
The 12496 is a Philips/Osram part number designating a 12V halogen bulb for specialty automotive applications. It does not carry a universal ANSI or ECE designation, meaning it is sourced by manufacturer part number rather than a standardized code.
The front turn signal on the Mercedes-Benz CLA45 AMG shifted from the 3457NA (2014-2018) to the 12496 in 2019 and then to the PY21W in 2020, reflecting three different bulb types across the production run.
The 3457NA is specified exclusively for the front turn signal position on 2014-2018 models equipped with halogen capsule headlamps. It does not appear in any rear turn signal position across any model year in these specifications.
The PY21W and the 3457NA are not interchangeable. The PY21W uses a BAU15s bayonet base, while the 3457NA uses a wedge-style T25 base. The wattage and filament count also differ between the two types.
The 12496 appears in both the front and rear turn signal positions, making it the only bulb type in these specifications that is shared across both locations, though not necessarily within the same model year.
Several model years carry the qualifier "With Halogen Capsule Headlamps," indicating that the listed bulb size applies specifically to that headlamp configuration rather than to all trim or equipment variants of that year.
The rear turn signal for 2017 uses the PY21W, while the front turn signal for the same year uses the 3457NA, meaning the front and rear positions require different bulb types on that model year.