The Mazda B4000 front turn signal requires a 3157NA or 3157 bulb size, while the rear turn signal uses 2456, 2356, or 3156 bulb sizes. The replacement chart covers 1994 through 2009 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mazda B4000 front turn signal uses the 3157NA bulb for model years 2000-2009. This is a dual-filament T25 wedge bulb rated at 12V with a 27W high-filament and 7W low-filament output, distinguished by its natural amber glass envelope, which produces an amber signal color without relying on a colored lens or housing.
For model years 1994-1999, the Mazda B4000 front turn signal uses the 3157 bulb instead. The 3157 shares the same T25 wedge base, dual-filament design, and 12V/27W/7W electrical ratings as the 3157NA, but its glass is clear rather than natural amber.
The 3157 and 3157NA are physically interchangeable due to their identical base type and electrical ratings. However, substituting a clear 3157 in a position designed for the 3157NA may alter the output color of the signal if the housing does not provide its own amber filtering.
The rear turn signal position on the B4000 does not use a single consistent bulb type across all model years. Three distinct bulb types, the 2456, 2356, and 3156, are specified across the 1994-2009 production range, and these types are not interchangeable with one another.
The 3156 is a single-filament T25 wedge bulb rated at 12V and 27W. It shares the same T25 wedge base form as the 3157 and 3157NA front bulbs but carries only one filament, making it electrically and functionally distinct from those dual-filament types.
The 2356 uses a BAY15d bayonet base and is a dual-filament bulb rated at 12V. The BAY15d base is a double-contact offset-pin bayonet fitting, which is physically incompatible with the wedge-base sockets used by the 3157, 3157NA, and 3156 bulbs.
The 2456 is a festoon-type bulb rated at 12V, intended for specialty applications. Festoon bulbs are held in place by spring-loaded end caps rather than a base socket, making them physically incompatible with both wedge and bayonet socket types.
All bulb types specified for the B4000 conform to ANSI standards applicable in the United States and Canada, indicating standardized electrical and dimensional tolerances within each respective bulb family.
The rear turn signal specification for the B4000 varies on a year-by-year basis rather than following a continuous generational pattern. For example, the 2003 model year uses the 3156, while the immediately adjacent 2002 and 2004 model years both use the 2456, requiring per-year verification before replacement.
Because the rear turn signal socket type differs depending on the model year, a replacement bulb selected by wattage or voltage rating alone is insufficient for confirming fitment. Base type must also be matched to the specific year's socket configuration.