Ford Transit Turn Signal Bulb Size

Ford Transit front inner and front turn signal bulbs utilize 3457NA size, while rear turn signal bulbs use PY21W or 3057 size. The replacement chart covers vehicle production years spanning 2015 to 2023 with corresponding bulb specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Front Inner Turn Signal

Years	US Type	EU Type	Shop
2015-2020	3457NA	PY27/7W	Check Price

Front Turn Signal

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2023	3457NA	PY27/7W	Check Price
2020	3457NA	PY27/7W	Check Price
2017-2018	3457NA	PY27/7W	Check Price
2015-2016	12961 (Mirror)	12961	Check Price

Rear Turn Signal

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2023	7507	PY21W	Check Price
2015-2020	3057	3057	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament wedge bulb (T25), natural amber glass. 12V, 27W/7W.	3457NA	Check Price
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961	Check Price
ECE standard (Europe & worldwide). Single-filament amber bulb with BAU15s bayonet base. 12V, 21W.	PY21W	Check Price
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3057	Check Price

Other Locations

Additional Notes

The 3457NA is the most frequently specified bulb across the Ford Transit turn signal positions, appearing in the Front Inner Turn Signal for 2015-2020 and the Front Turn Signal for 2017-2018 and 2020-2023.
The 3457NA is an ANSI-standard dual-filament T25 wedge bulb rated at 12V with a 27W high filament and 7W low filament. Its natural amber glass produces the required amber signal color without relying on a colored lens.
The 3057 shares the same T25 wedge form and 12V, 27W/7W dual-filament rating as the 3457NA but lacks the natural amber glass coating, making the two bulbs physically similar yet visually distinct in output.
The Ford Transit (2015-2020) Rear Turn Signal uses the 3057, while the 2023 model year uses the PY21W, reflecting a shift to a different base type and filament configuration for that position.
The PY21W follows the ECE standard used in European and worldwide markets. It is a single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s offset bayonet base, which is not interchangeable with the standard BA15s base found on many other automotive bulbs.
The Ford Transit (2015-2016) Front Turn Signal uses the 12961, designated for the mirror position. This is a miniature T10 wedge bulb with a W2.1x9.5d base, rated at 12V and 5W, a significantly lower wattage than the 3457NA used in other front turn signal positions.
The W2.1x9.5d base of the 12961 is physically incompatible with the T25 wedge base of the 3457NA, meaning the mirror-mounted front turn signal socket on 2015-2016 models does not accept the bulb used in other front signal positions on the same vehicle.
The BAU15s bayonet base of the PY21W features an offset pin arrangement specifically designed to prevent installation of non-amber bulbs in turn signal sockets, distinguishing it from the standard BA15s base used on clear single-filament bulbs of similar wattage.