Mercedes-Benz ML350 Turn Signal Bulb Size

Additional Notes

• The PY21W is an ECE-standard single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s bayonet base. It appears across multiple positions and model years of the Mercedes-Benz ML350, serving both front inner turn signal and rear turn signal functions.
• The BAU15s base of the PY21W is offset, meaning it is not interchangeable with the standard BAY15d bayonet base used on bulbs such as the 1157NA and 1034NA, despite those bulbs sharing a similar physical form factor.
• The PY24WNA is an ANSI-standard amber bulb rated at 12V and 24W, using a PGU20-4 base. It is the designated front turn signal bulb for the ML350 with halogen capsule headlamps across the 2012-2015 model years.
• The PGU20-4 base of the PY24WNA is a push-in connector type specific to that bulb family, making it incompatible with the wedge or bayonet bases found in other bulbs listed in these specifications.
• The 3457NA is a dual-filament T25 wedge bulb rated at 12V with a 27W main filament and a 7W secondary filament. Its natural amber glass produces the amber signal color without requiring a separate amber lens.
• The 3357NA is a single-filament T25 wedge bulb rated at 12V and 27W, also with natural amber glass. Although it shares the same T25 wedge base as the 3457NA, the absence of a second filament means the two are not functionally interchangeable in dual-filament applications.
• The front turn signal position of the ML350 used four different bulb types across the 2003-2015 model range, specifically the 1157NA, 1034NA, 3357NA, 3457NA, and PY24WNA, reflecting generational changes in headlamp system design and regional lighting standards.
• For the 2006 and 2007 ML350, the front turn signal bulb specification is conditional on headlamp type. The 3457NA or 3357NA applies with standard configurations, while HID headlamp-equipped vehicles use different bulbs, indicating that headlamp system type directly affects turn signal bulb selection in those years.
• The 1034NA and 1157NA are both dual-filament bulbs sharing the BAY15d bayonet base and a 12V rating with a 21W main filament and 5W secondary filament. The 1034NA is a variant of the 1157NA, and the two are functionally similar, though they are listed as distinct part numbers in these specifications.
• The 12496 is a Philips/Osram part number designation for a 12V halogen bulb used in specialty applications. It is listed as the rear turn signal bulb for the ML350 across several non-consecutive model years, including 2003-2004, 2006-2007, and 2011.