Nissan Altima Back Up Light Bulb Size

The Nissan Altima back up light utilizes bulb sizes 921, P21W, and 1156 for various lighting applications across the vehicle. Available data for the specified components covers the range from 1993 to 2023.

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

Bulb Size by Year Range

Years	Bulb Size
2022-2023	921
2014-2020	921
2009	921
1998-2006	921
1993-1997	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Nissan Altima back up light uses one of two bulb types across its model years: the 921 and the 1156, both of which are ANSI-standardized bulbs for the US and Canadian markets.
The 921 is a T15 wedge-base bulb rated at 12V and 16W. Its wedge-style base means it is held in place by friction within the socket rather than by a locking mechanism.
The 1156 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W. The bayonet base requires a push-and-twist motion to seat and release from its socket, which is physically incompatible with a wedge-style socket.
Because the 921 uses a wedge base and the 1156 uses a bayonet base, these two bulb types are not interchangeable despite both operating at 12V.
The Nissan Altima (1993-1997) uses the 1156 bulb for the back up light position.
From 1998 onward, the Altima back up light specification shifts to the 921 bulb, which draws 16W compared to the 21W of the 1156.
The 921 bulb is specified across the widest range of model years in these specifications, covering 1998-2023 with the exception of 2010-2013 and 2021.
The wattage difference between the two bulb types is notable: the 1156 at 21W draws more power than the 921 at 16W, which reflects a difference in filament design and light output characteristics between the two standards.