Subaru XT Dome Light Bulb Size

The Subaru XT dome light utilizes bulb size 67 and bulb size DE3175 for interior illumination. Available information covers the specific time period from 1985 through 1991.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1991	67
1985-1990	DE3175

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67
ANSI standard (US & Canada). Festoon bulb, 31mm length, end-cap contacts. 12V.	DE3175

Other Locations

Additional Notes

The DE3175 is the dome light bulb specified for the Subaru XT across the 1985-1990 model years, making it the predominant fitment across the production run covered by these specifications.
The DE3175 is a festoon-type bulb, meaning it is cylindrical in form and makes electrical contact through metal caps at each end rather than through a base socket. Its 31mm length is a critical fitment factor, as festoon bulbs must match the span of the lamp holder precisely.
For the 1991 model year, the Subaru XT uses a bulb size 67 instead of the DE3175, representing a change in dome light bulb type relative to earlier model years.
The size 67 bulb uses a BA15s bayonet base, which is a single-pin bayonet mount. This base type is physically incompatible with the end-cap festoon holder used by the DE3175, meaning the two bulbs are not interchangeable despite both serving the dome light function.
The size 67 operates at 12V and 8W. It is a single-filament bulb and is described as a lower wattage variant of the 1156, which shares the same BA15s base but draws significantly more current. Substituting a 1156 in place of a size 67 socket would exceed the intended wattage for that circuit.
Both the DE3175 and the size 67 conform to ANSI standards applicable in the United States and Canada, indicating standardized specifications for voltage, base type, and physical form within those markets.
The DE3175 specification does not include a wattage value in these specifications, whereas the size 67 is explicitly rated at 8W. This distinction is relevant when sourcing replacement bulbs, as wattage affects heat output and electrical load on the dome light circuit.