Subaru WRX STI Dome Light Bulb Size

The Subaru WRX STI dome light requires a DE3175 bulb size for proper installation and function within the interior cabin. Available data covers the specific range from 2015 through 2020 for the specified lighting component.

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
2015-2020	DE3175

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 31mm length, end-cap contacts. 12V.	DE3175

Other Locations

Additional Notes

The Subaru WRX STI uses the DE3175 bulb size for the dome light across the 2015-2020 model years.
The DE3175 is classified as a festoon-type bulb, meaning it is cylindrical in shape and makes electrical contact through metal caps at each end rather than through a base socket.
The DE3175 operates at 12 volts, which is standard for automotive interior lighting systems.
The 31mm length of the DE3175 is a critical fitment factor, as festoon bulbs must physically span the contact points of the fixture to maintain a circuit.
The DE3175 designation follows ANSI standards applicable in the United States and Canada, indicating the bulb conforms to a defined set of electrical and physical specifications within those markets.
Because the DE3175 is an ANSI-standardized festoon bulb, aftermarket and LED replacement options that match the 31mm length and end-cap contact configuration are generally considered interchangeable with the original fitment.