The Audi Q7 turn signal requires a P21W bulb size for proper installation and function within the lighting assembly. Data for the specified component covers the range from 2007 to 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The front turn signal on the Audi Q7 uses two distinct bulb families across its model years: the 12174-series for 2018-2019 and 2021-2024, and the H21W for 2007-2012.
The 12174NA is a natural amber glass bulb rated at 12V. Its amber coloring is built into the glass itself rather than applied as a coating, which is a common OEM approach for achieving ECE-compliant amber signaling without a colored lens.
The 12174SV is a Philips SilverVision variant also rated at 12V. Its enhanced coating distinguishes it from the 12174NA, and the two carry different part numbers despite sharing the same base application on the Q7, specifically the 2021 front turn signal.
The H21W uses a BAY9s base, which is an offset-pin bayonet fitting. This base type is not interchangeable with the BA15s or BAU15s bases found on other bulbs in these specifications, making substitution between H21W and other single-filament 21W types physically incompatible.
For the 2019 and 2018 Audi Q7 front turn signal, the 12174NA fitment is conditional on the vehicle being equipped with HID headlamps. The 2010-2012 H21W fitment is similarly conditional on halogen capsule headlamps.
The rear turn signal on the Audi Q7 uses the 7506 bulb for 2007-2015, making it the most consistently specified bulb across both sub-parts in these listings. The 7506 is the North American market designation for what is internationally classified as the P21W.
The PY21W uses a BAU15s bayonet base, which has an offset pin at 7.5 degrees. This offset is specifically designed to prevent substitution with the BA15s-based P21W, even though both are single-filament 21W bulbs rated at 12V. The 2018 rear turn signal on the Audi Q7 uses the PY21W.
The P21W uses a BA15s bayonet base and is listed for the 2007-2009 Audi Q7 rear turn signal alongside the 7506. Both the P21W and 7506 are single-filament 21W bulbs at 12V, with the P21W being the ECE-standard designation and the 7506 being its North American equivalent.
The H21W, PY21W, and P21W are all ECE-standard bulbs rated at 12V and 21W, but each uses a different base type, BAY9s, BAU15s, and BA15s respectively. These base differences make them non-interchangeable despite their identical voltage and wattage ratings.
The 2021 front turn signal specification stands apart from adjacent years in that it lists the 12174SV rather than the 12174NA, indicating a different approved bulb variant for that model year relative to 2023-2024.