Audi TT RS Quattro front turn signal bulbs use 12174SV, 12496, or H21W sizes, while rear turn signal bulbs use 921 size. The chart covers 2012 to 2021 replacement bulb specifications for this vehicle.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H21W bulb follows the ECE standard used in Europe and worldwide markets. It is a single-filament signalling bulb rated at 12V and 21W, fitted with a BAY9s bayonet base. On the Audi TT RS Quattro, this bulb applies specifically to the 2012 front turn signal position when the vehicle is equipped with halogen capsule headlamps.
The 12496 is a 12V halogen bulb designated for specialty applications, produced under both Philips and Osram part numbering. It serves the front turn signal on the 2012 TT RS Quattro when fitted with HID headlamps, and also on the 2013 model year, indicating that headlamp type is a direct factor in front turn signal bulb selection for the 2012 configuration.
The 12174SV carries a Philips SilverVision designation and is a 12V halogen bulb with an enhanced reflective coating. It is specified for the 2021 front turn signal position, representing a distinct bulb type from those used in the 2012-2013 model years.
The 921 is an ANSI-standard wedge bulb of the T15 form factor, rated at 12V and 16W. It is the specified rear turn signal bulb for both the 2012 and 2013 model years, making it the only bulb in these specifications shared across consecutive rear turn signal positions.
The front turn signal position on the 2012 model requires attention to headlamp type before a replacement bulb is selected, as the H21W and 12496 are not interchangeable with each other despite both serving the same lighting position on the same model year.