Porsche 914 Back Up Light Bulb Size

The Porsche 914 back up light uses 1156 and P21W bulb sizes for the rear illumination components. Data for the specific lighting requirements covers the period from 1970 through 1976.

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
1970-1976	1156

Bulb Specifications

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

Other Locations

Additional Notes

The Porsche 914 uses the 1156 bulb for the back up light across all listed model years, spanning 1970-1976.
The 1156 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard used in the United States and Canada.
The 1156 operates on a 12-volt electrical system, which is consistent with standard automotive electrical architecture of that era.
At 21 watts, the 1156 produces a relatively high output for an incandescent single-filament bulb, which is typical for back up light applications requiring adequate rear illumination.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width. The single-contact design corresponds directly to the bulb's single-filament construction.
Because the 1156 is a single-filament bulb, it serves one dedicated function per socket. It is not interchangeable with dual-filament variants such as the 1157, which shares a similar bayonet base style but carries a second contact pin and filament for a separate function.