The Mazda 323 uses a brake light component with a specific 1157 bulb size for the lighting system. Data for the specified vehicle covers the period from 1986 through 1994.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mazda 323 brake lights use the 1157 bulb across the 1986-1994 model years.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve both brake and tail light functions.
The BAY15d bayonet base features two offset pins at different heights, which prevents incorrect insertion and ensures the two filaments are connected to the correct circuits.
The 1157 follows the ANSI standard, which is the governing specification for bulbs sold in the United States and Canada.
The center high mount stop light on the 1992-1994 Mazda 323 uses the 921 bulb, a single-filament wedge-type T15 bulb rated at 12V and 16W.
The 1990-1991 Mazda 323 center high mount stop light uses the P21W bulb instead of the 921. The P21W follows the ECE standard, which governs lighting equipment across Europe and many other markets worldwide.
Although the 921 and P21W are both rated at 12V and share a similar wattage range, they are not interchangeable. The 921 uses a wedge base while the P21W uses a BA15s single-pin bayonet base, making socket compatibility a critical fitment consideration.
The P21W is a single-filament bulb, as is the 921. Neither is suited for dual-function applications the way the 1157 is.
The shift from P21W to 921 in the center high mount stop light between the 1991 and 1992 model years reflects a change in base standard from ECE to ANSI specification for that position.