Chevrolet Impala Back Up Light Bulb Size

The Chevrolet Impala back up light utilizes 7440, 921, 2057, 1156, 1073, and P21W bulb sizes depending on the specific production version. Available information spans a range from 1958 through 2020.

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
2014-2020	7440
2000-2013	921
1994-1996	2057
1964-1985	1156
1962-1963	1073
1958-1961	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Brighter variant of 1157. 12V, 26.9W/8W.	2057
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	1073

Other Locations

Additional Notes

The Chevrolet Impala back up light specifications reference four distinct bulb types across its model history: the 7440, 921, 2057, 1156, and 1073, each belonging to the ANSI standard used in the United States and Canada.
The 1156 bulb is the most frequently specified type across the Impala's back up light history, covering model years 1958-1964 and 1965-1985, with the exception of 1962-1963. It is a single-filament bulb with a BA15s bayonet base rated at 12V and 21W.
The 921 wedge bulb (T15) is the second most commonly specified type, covering the Chevrolet Impala from 2000-2013. It operates at 12V and 16W, making it a lower-wattage option compared to the 7440 that succeeded it.
The 7440 is a single-filament T20 wedge bulb rated at 12V and 21W. It is specified for the Impala across model years 2014-2020, representing the most recent bulb type in these specifications.
The 921 and 7440 are both wedge-base bulbs, but they differ in size class, with the 921 using a T15 form factor and the 7440 using a larger T20 form factor. These two types are not interchangeable despite their shared wedge-base design.
The 2057 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 26.9W high-filament and an 8W low-filament. It is specified only for the 1994-1996 Impala model years.
The 2057 is described as a brighter variant of the 1157. Its dual-filament design and BAY15d base make it physically and electrically incompatible with the single-filament 1156, which uses a BA15s base, despite both being bayonet-style bulbs.
The 1073 is a single-filament bulb sharing the BA15s bayonet base with the 1156, but it operates at a lower wattage of 13W versus the 1156's 21W. It is specified for the Impala in 1962-1963 only.
Although the 1073 and 1156 share the same BA15s bayonet base, the wattage difference between the two means substituting one for the other may not meet the original electrical specification for those model years.
The back up light bulb type for the Chevrolet Impala changed at least four times across the span covered by these specifications, shifting from the 1156 and 1073 bayonet-base bulbs in earlier decades to the wedge-base 921 and 7440 types in later model years, with the 2057 appearing only in the mid-1990s.