For the 2018 Subaru WRX, headlight bulb fitment depends on the installed headlight type. Low beams use H11 with halogen headlights, while LED headlights use an integrated LED low beam. High beams are listed as either 9005 or LED, so confirm the headlight assembly before ordering.
Fog light options also vary: listings include H11 LED, H16 LED, and LED with LED headlights. Daytime running lights use 9005 with halogen headlights and LED with LED headlights. The front and rear turn signals use amber 7440A bulbs, while reverse lights use 921.
Several exterior lamps are factory LED, including the brake, center stop, tail, and—on applicable equipment—the LED headlight-related lighting. License plate and trunk lighting may use 168 or 917. Dome and map lights use DE3175, and both front and rear side markers use 168NA.