Mazda 3 brake bulbs utilize a 7443 size, while the center high mount stop light requires a 921 size bulb. The replacement chart covers vehicle production years spanning 2004 to 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mazda 3 uses the 7443 bulb for brake lighting across the 2004-2009 model years.
The 7443 is a dual-filament wedge bulb of the T20 type, rated at 12V with a wattage split of 21W for the high-intensity filament and 5W for the low-intensity filament. This dual-filament design allows a single bulb to serve both brake and tail light functions.
The 7443 conforms to ANSI standards applicable in the United States and Canada.
The Center High Mount Stop Light on the Mazda 3 uses the 921 bulb across the 2004-2009 model years.
The 921 is a single-filament wedge bulb of the T15 type, rated at 12V and 16W. Its single-filament construction means it serves only one lighting function, consistent with its use in a dedicated stop light position.
The 921 also conforms to ANSI standards applicable in the United States and Canada.
The T20 and T15 designations refer to the outer width of the wedge base, with T20 being physically larger than T15. These two bulb types are not interchangeable with each other due to differences in base size, wattage, and filament count.
The 7443 and 921 share the same 12V operating voltage, which is standard for automotive electrical systems, but their wattage ratings and filament configurations differ, reinforcing that each position requires its specified bulb type.