The Audi A3 fog light utilizes H21W and H7 bulb sizes depending on the specific version of the lighting component. Data for the bulb sizes covers the range from 2006 to 2023.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Audi A3 front fog light draws from three halogen bulb types across its model years: H11, H8, and H7. The rear fog light uses the H21W exclusively across all listed model years.
The H11 is the most frequently specified front fog light bulb in the Audi A3, appearing in the 2022-2024, 2017, 2013, and 2006-2012 model years. It operates at 12V and 55W, uses a PGJ19-2 base, and carries ECE approval for use in Europe and worldwide, with additional approval in the United States.
The H8 bulb appears in the Audi A3 front fog light position for the 2014-2016 and 2020 model years. It shares the same single-filament halogen construction as the H11 but operates at a lower wattage of 35W and uses a PGJ19-1 base rather than the PGJ19-2 found on the H11. The two bulbs are not interchangeable due to their differing base types.
The H7 bulb is specified for the Audi A3 front fog light in the 2007 model year and as a variant in the 2006 and 2008 model years. It uses a PX26d base, which is physically distinct from both the PGJ19-1 and PGJ19-2 bases used by the H8 and H11, making cross-substitution between these types incompatible.
For the 2006-2008 Audi A3, two front fog light bulb sizes are listed depending on trim configuration. Vehicles without the S-Line bumper take an H7, while the standard entry takes an H11, indicating that bumper trim level is a determining factor in bulb fitment for those years.
The H21W rear fog light bulb uses a BAY9s base and is rated at 12V and 21W. It is classified as a signalling bulb rather than an illumination bulb, which reflects its lower wattage relative to the front fog light bulbs. Its ECE approval covers Europe and worldwide markets.
The 2019 Audi A3 rear fog light specification carries an "Inner" position designation for the H21W, distinguishing it from other listed years where no positional qualifier is noted.
The H11 and H8 share a visual and dimensional similarity in their PGJ19-series base family, but their base retention tabs are positioned differently, making them non-interchangeable despite their outward resemblance. Installing an incorrect type risks improper seating and potential electrical incompatibility.