There are a variety of switches and sensors fitted to your Audi A4. These include but aren't limited to brake light and reverse light switches as well as windscreen washer bottle fluid level sensors. Your car is reliant on these sensors being fully functioning to keep you and other road users safe. orangespanner stock a whole host of sensors from the best brands, all at great prices. If you can't find what you are looking for then please contact a member of the team who will be happy to assist you.