Geo Metro high beam and low beam headlight bulbs utilize 9003, H4666, or 9004 bulb sizes depending on production specifications. The replacement chart covers 1989 through 1997 model years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Geo Metro's halogen capsule headlamp fitment splits across two bulb types depending on model year. The 9004 bulb applies to 1989-1994 models, while the 9003 bulb applies to 1995-1997 models.
Both the 9003 and 9004 are dual-filament halogen bulbs, meaning a single bulb serves both high and low beam functions. This is reflected in the specifications, where the same bulb size is listed under both the high beam and low beam positions for each year.
The 9003 operates at 12V with a 60W high beam filament and a 55W low beam filament. It uses a P43t base.
The 9004 also operates at 12V but carries a higher-wattage high beam filament at 65W and a lower-wattage low beam filament at 45W. It uses a P29t base.
The P43t and P29t bases are physically incompatible with each other, so the 9003 and 9004 are not interchangeable despite both being dual-filament halogen bulbs rated at 12V.
The Geo Metro with sealed beam headlamps uses the H4666 across all model years from 1989-1997. The H4666 is a rectangular sealed beam unit in which the lens, reflector, and filament form a single assembly that is replaced as a whole rather than as an internal bulb.
All three bulb types listed, the 9003, 9004, and H4666, conform to ANSI standards applicable in both the United States and Canada.
Because the halogen capsule and sealed beam headlamp systems use entirely different replacement components, the headlamp type installed on a specific vehicle must be confirmed before a replacement part is selected.