Nissan 240Z front turn signal bulbs use 1157 size, while rear turn signal bulbs use P21W or 1157 size. The replacement chart covers 1970 to 1973 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 bulb follows the ANSI standard used in the United States and Canada. It is a dual-filament bulb rated at 12V with a 21W bright filament and a 5W dim filament, mounted on a BAY15d bayonet base.
The P21W bulb follows the ECE standard used in Europe and worldwide markets. It is a single-filament signalling bulb rated at 12V, 21W, and uses a BA15s bayonet base.
The BAY15d base of the 1157 and the BA15s base of the P21W are physically distinct and not interchangeable. The BAY15d has offset locating pins to accommodate its dual-filament design, while the BA15s has a single-pin configuration.
The Nissan 240Z front turn signal position uses the 1157 bulb across all model years covered, specifically 1970-1973.
The Nissan 240Z rear turn signal position uses the 1157 bulb for model years 1970-1972.
The 1973 rear turn signal specification diverges from the prior three years, calling for the P21W rather than the 1157. This reflects a change in base type, filament count, and regional standard for that position in that year.
Because the 1157 is a dual-filament bulb, it is capable of serving both a high-intensity turn signal function and a lower-intensity parking or running light function within a single housing. The P21W, being single-filament, serves only one lighting function per bulb.
Substituting a P21W for a 1157 in a socket designed for the BAY15d base would not be physically compatible due to the differing pin configurations of the two bayonet bases.