The Mercedes-Benz GLA45 AMG front turn signal uses bulb sizes 12496, 3357NA, or 3457NA, while the rear turn signal requires 12496 or PY21W size bulbs. The replacement chart covers 2015 to 2019 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 GLA45 AMG turn signal specifications across all listed years apply exclusively to vehicles equipped with halogen capsule headlamps.
The 12496 is a halogen bulb operating at 12V, identified by a Philips/Osram part number rather than an ANSI or ECE standard designation, placing it in a specialty application category.
The 3357NA and 3457NA both follow ANSI standards used in the US and Canadian markets. Both operate at 12V and share a T25 wedge form factor with natural amber glass, though they differ in filament count: the 3357NA carries a single filament rated at 27W, while the 3457NA carries dual filaments rated at 27W and 7W respectively.
The dual-filament construction of the 3457NA means it is not a direct substitute for the single-filament 3357NA, despite the two bulbs sharing the same voltage, wattage on the primary filament, and physical base type.
The PY21W follows the ECE standard used in European and worldwide markets. It uses a BAU15s offset bayonet base, operates at 12V, and produces 21W through a single filament. The offset pin configuration of the BAU15s base prevents incorrect installation.
For the 2017-2018 front turn signal positions, the GLA45 AMG uses the 3357NA, a single-filament ANSI bulb, while the rear positions for those same years use the PY21W, an ECE-standard bulb with a different base type entirely.
In 2019, the GLA45 AMG uses the 12496 in both the front and rear turn signal positions, making it the only year in the listed range where both positions share an identical bulb.
The 2015-2016 front turn signal position uses the 3457NA, a dual-filament bulb, while the rear position for those same years uses the 12496, a specialty halogen type. The two are not interchangeable due to differences in base type, filament count, and wattage.
Because the PY21W uses a BAU15s bayonet base and the ANSI-standard bulbs use a wedge base, no cross-substitution is possible between PY21W and any of the 3357NA, 3457NA, or 12496 types without a socket adapter.