Nissan 280Z Back Up Light Bulb Size

Additional Notes

• The P21W is the sole bulb type listed for the back up light position across all four model years covered in the Nissan 280Z specifications, spanning 1975-1978.
• The P21W is an ECE-standard single-filament bulb, meaning it carries one filament dedicated to a single lighting function, which in this application is the reverse/back up light.
• The P21W operates at 12 volts and 21 watts, placing it in the mid-range of automotive signalling bulb wattage and consistent with standard reverse light output requirements.
• The P21W uses a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single-contact base rather than a dual-contact one.
• The BA15s single-contact base is a critical fitment detail for the Nissan 280Z, as the visually similar BA15d base carries two contacts and is not interchangeable despite sharing the same 15mm base width.
• The P21W designation follows ECE (Economic Commission for Europe) standardization, meaning the bulb is governed by internationally recognized performance and construction requirements rather than SAE standards used in North American automotive contexts.
• The consistent use of the P21W across 1975-1978 indicates no bulb specification change occurred within the production span covered by these records.