The Mercedes-Benz SLK350 front turn signal bulb utilizes 3457NA or 3357NA size, while the rear turn signal bulb requires 12496, PY21W, or 1156NA size. The replacement chart covers 2005 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 3457NA bulb is the most frequently specified front turn signal bulb across the Mercedes-Benz SLK350 model range, covering the 2005-2006 and 2008-2016 model years.
The 3457NA is a dual-filament T25 wedge bulb rated at 12V with a 27W main filament and a 7W secondary filament, coated with natural amber glass to produce the required amber signal color without a separate amber lens.
The 3357NA, specified for the 2007 front turn signal, is a single-filament T25 wedge bulb rated at 12V and 27W. Although it shares the same T25 wedge form factor and natural amber glass as the 3457NA, it lacks the second filament, making the two bulbs functionally distinct despite their physical similarity.
The 2012-2016 front turn signal position carries an additional fitment condition, specifying the 3457NA only for vehicles equipped with halogen capsule headlamps. This condition indicates that alternative headlamp configurations on those model years may require a different bulb.
The rear turn signal position on the Mercedes-Benz SLK350 uses three different bulb types across the 2005-2011 model years, reflecting variation in regional standards and lamp assembly design across production periods.
The PY21W is an ECE-standard single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s offset bayonet base. The offset pin arrangement of the BAU15s base physically prevents substitution with bulbs using the standard BA15s base, such as the 1156NA.
The 1156NA, specified for the 2005-2006 rear turn signal, uses a BA15s bayonet base and is rated at 12V and 21W. Its natural amber glass serves the same color function as the PY21W, but the differing base types mean the two bulbs are not interchangeable.
The 12496 is a Philips/Osram part number designation for a 12V halogen bulb used in specialty lamp applications, specified for the 2008 and 2011 rear turn signal positions. Its proprietary designation indicates it is not cross-referenced under a universal ANSI or ECE standard number.
The rear turn signal specifications cover only the 2005-2011 model years, while the front turn signal specifications extend through 2016, reflecting differences in the scope of data provided for each lamp position.
The coexistence of ANSI-standard bulbs such as the 3457NA and 1156NA alongside ECE-standard bulbs such as the PY21W within the same model's specifications reflects the SLK350's distribution across both North American and international markets during its production run.