There are several discount codes available for Istanbul E-pass. One of them offers a 25% discount. Another code provides a 45% discount on orders over €133. There's also a site-wide deal that gives an exclusive 40% off on all orders. Please note that these codes may be subject to terms and conditions, and it's recommended to check the validity of these codes on the respective websites. If these codes are not working or expired, it's suggested to check the official Istanbul E-pass website for the latest offers and discounts.