Subaru Outback Turn Signal Bulb Size

Additional Notes

• The 7440NA is the most widely used bulb across the Subaru Outback turn signal specifications, serving as the rear turn signal bulb for all listed model years from 2008-2024 and as the front turn signal bulb for 2013-2022. It is a single-filament T20 wedge bulb rated at 12V and 21W, with natural amber glass that produces the required amber signal color without a separate amber lens or coating.
• The "NA" suffix found on several bulb types in these specifications, including the 7440NA, 7444NA, 3357NA, and 3457NA, denotes natural amber glass. This coloring is built into the glass envelope itself rather than applied as a coating, and it is used in housings with clear or non-amber lenses to meet amber turn signal output requirements.
• The 7444NA, used for the front turn signal on the Subaru Outback from 2019-2022, is a dual-filament variant of the T20 wedge form factor, rated at 12V with a 21W main filament and a 5W secondary filament. Its dual-filament design distinguishes it from the single-filament 7440NA despite sharing the same T20 wedge base and natural amber glass.
• The 1157, specified for the front turn signal on the 2023-2024 Outback, uses a BAY15d bayonet base rather than a wedge base, making it physically incompatible with the T20 wedge sockets used in earlier model years. It is a dual-filament bulb rated at 12V, 21W/5W, and represents a distinct socket type from all other bulbs listed in these specifications.
• The 7440 and 7440NA are both single-filament T20 wedge bulbs rated at 12V and 21W, with the sole difference being the presence of natural amber glass in the 7440NA. The 7440 without the NA suffix was specified for the front turn signal on the Outback from 2010-2012, while the 7440NA replaced it from 2013 onward in that position.
• The 2008 and 2009 Outback front turn signal specifications call for T25 wedge bulbs rather than T20 types. The 2009 uses the 3357NA, a single-filament T25 bulb rated at 27W, while the 2008 uses the 3457NA, a dual-filament T25 bulb rated at 27W/7W. The T25 form factor is physically larger than the T20 and the two are not interchangeable.
• The front and rear turn signal positions on the Outback do not share the same bulb type across all years. While the rear position uses the 7440NA uniformly from 2008-2024, the front position has used six different bulb types across the same span, reflecting changes in socket design and filament configuration between model generations.
• All bulbs listed in these specifications conform to ANSI standards applicable in the United States and Canada, operating on a 12V electrical system consistent with standard automotive electrical architecture.