Dodge Neon Back Up Light Bulb Size

Additional Notes

• The Dodge Neon uses two distinct back up light bulb sizes across its production run, with the 921 fitted to model years 2000-2005 and the 3157 fitted to model years 1995-1999.
• The 921 is a single-filament wedge bulb rated at 12 volts and 16 watts, conforming to the T15 form factor under the ANSI standard used in the United States and Canada.
• The 3157 is a dual-filament wedge bulb rated at 12 volts, with filaments rated at 27 watts and 7 watts respectively, conforming to the T25 form factor under the same ANSI standard.
• Because the 921 and 3157 are both wedge-type bulbs, their base style may appear similar, but the T15 and T25 designations indicate different physical sizes, making the two bulbs non-interchangeable.
• The dual-filament design of the 3157 means it carries two separate circuits within a single bulb, a characteristic that distinguishes it functionally from the single-filament 921 used in later Neon model years.
• The higher wattage filament of the 3157 at 27 watts produces noticeably more light output than the 921 at 16 watts, a relevant distinction when considering the reverse lighting performance of each generation of the Dodge Neon.
• Both bulb types operate on a 12-volt electrical system, consistent with standard automotive electrical architecture.