For the 2009 Audi TT, both the low-beam and high-beam headlights use D1S bulbs. This fitment is listed for the headlights without a separate halogen-versus-HID distinction, so verify the existing headlamp assembly before ordering.
Fog-light options are listed as H11 LED and H16 LED. Front turn-signal and parking-light fitment depends on the headlight configuration:
- With halogen headlights: front turn signal 64136; parking light and front side marker 2827.
- With HID headlights: front turn signal 7507; parking light and front side marker 64132.
Other notable fitments include 921 bulbs for the reverse lights and rear turn signals, 7506R for the brake and tail lights, and a factory LED center stop light. The daytime-running light uses 7506, while the license-plate and courtesy lights use 6418. Glove-box, map, and trunk lighting may use either 2825 or 98, so compare the removed bulb and socket before replacing.