2021 Audi S4 Bulb Size

Goal: help you quickly match the correct bulb sizes for a 2021 Audi S4 so you avoid trial-and-error and wasted time. Many owners face confusion about front, rear, and interior lamps; this chart solves that problem by consolidating OEM sizes and common aftermarket options. Prerequisites and step by step: I assume you know which lamp assembly needs replacement and can read the socket markings. Use the chart to identify the socket type, compare the recommended bulb family, and pick the appropriate lumen or color trade-off for your needs. Note constraints like CAN-bus compatibility and fitment depth. Validation, troubleshooting, and wrap up: validate by checking the part numbers on removal and test before final reassembly. If you encounter flicker or dash warnings, try a CAN-bus compatible resistor or confirm connector seating. Affiliate disclaimer: some product links may earn me a commission at no extra cost to you; recommendations are based on hands-on experience and testing.