Honda Civic Headlight Bulb Size

Additional Notes

• The Honda Civic headlight specifications span five distinct bulb types across the 1973-1991 model years: H6024, H6054, 9004, 9005, and 9006, all conforming to ANSI standards applicable in the United States and Canada.
• The H6024 is a 7-inch round sealed beam unit operating at 12V. Because it is a sealed beam design, the entire unit is replaced rather than an internal filament or capsule. The Honda Civic used this type for the 1973-1981 model years across both high and low beam positions.
• The H6054 is a 5x7-inch rectangular sealed beam unit, also operating at 12V and also requiring full unit replacement. It appeared on the Civic for the 1982 and 1983 model years in both beam positions.
• The 9004 is a dual-filament halogen bulb with a P29t base, rated at 12V and carrying two wattage ratings: 65W for high beam and 45W for low beam. A single 9004 bulb serves both the high and low beam functions, which is reflected in the 1986 and 1987 Civic specifications where the same bulb size is listed for both positions.
• For 1988-1991, the Civic transitioned to a split-bulb arrangement, using the 9005 for high beam and the 9006 for low beam. These are separate single-filament bulbs, unlike the dual-filament 9004 they replaced.
• The 9005 carries a P20d base and is rated at 65W, while the 9006 uses a P22d base and is rated at 55W. Although both are single-filament halogen bulbs operating at 12V, their bases differ and the two types are not interchangeable with each other.
• The shift from sealed beam units to replaceable halogen bulbs occurred between the 1983 and 1986 model years, with the 9004 representing the first replaceable bulb type in the Civic headlight specifications.
• The 9004 and 9006 base designations, P29t and P22d respectively, follow IEC base coding conventions, where the letter-number combination describes the physical base configuration. These differences in base type prevent cross-fitting between incompatible bulb types.