For the 2001 Audi TT, the low-beam bulb depends on the factory headlight system: models with halogen headlights use an H1, while models with HID headlights use a D2S. The supplied fitment data does not list a separate high-beam bulb, so verify the headlight assembly before ordering.
- Fog lights may use either H3 or H3C.
- Front turn signals use 64136; rear turn signals and reverse lights use 7506.
- Brake and tail lights use 7528.
- The center stop light is an integrated LED unit.
- Front parking and side-marker lights use 64132; rear side-marker and trunk applications may use 2825 or 98.
- License plate and courtesy lights use 6418.
Confirm the existing bulb and housing markings when multiple options are listed, particularly for fog lights and rear side-marker or trunk lighting.