Mazda RX-8 Dome Light Bulb Size

The Mazda RX-8 dome light requires a DE3175 bulb size for proper installation within the interior overhead lighting fixture. Available data for the specified component covers the period from 2004 through 2011.

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
2004-2011	DE3175

Bulb Specifications

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

Other Locations

Additional Notes

The Mazda RX-8 uses the DE3175 bulb for the dome light across all listed model years, spanning 2004-2011.
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.
Festoon bulbs are held in place by spring-loaded clips that press against the end caps, a mounting method common in interior dome and map light applications.
The DE3175 has a 31mm length, which is the measurement between its two end contacts and determines whether it will seat correctly in the fixture.
The bulb operates at 12 volts, consistent with standard automotive electrical systems.
The DE3175 designation follows ANSI standards as applied in the United States and Canada, meaning the specification is defined by a recognized industry body rather than a proprietary manufacturer code.
Because festoon bulbs of different lengths are not interchangeable, a 28mm or 36mm festoon would not be a correct fit for the RX-8 dome light fixture, even if the voltage rating matched.