Audi S4 Fuel Door Failure: Common Fix Required

I had almost the exact same problem with my 2013 Audi S5 last winter. Have some experience with basic maintenance, but this was beyond my skills. The fuel filler door stopped responding completely when using the release button. The electric actuator was the culprit, turned out the linkage was defective and needed a full replacement. Initially tried the manual cable release as a temporary fix, but that didnt solve the underlying issue. Took it to a workshop where they diagnosed and replaced the complete lock actuator assembly. Total repair cost was 210 Euro including parts and labor. The repair solved all issues, no more error messages and the fuel flap works perfectly now. For a proper diagnosis, could you share: Do you hear any clicking sound when pressing the release button? Have you checked if the manual release cable works? Are there any other electrical issues with central locking? Did the problem start suddenly or gradually? This info would help determine if your issue matches what I experienced with the faulty actuator mechanism.

Last service done at 165000 KM. Thanks for the detailed reply. No clicking sound when pressing the release button. The manual cable release was my first attempt but it also failed to open the fuel flap. The central locking works fine on all doors, and this issue started suddenly during a rainstorm last week. The key fob functions all work normally, including the trunk release. Your experience with the electric actuator replacement sounds exactly like my situation. The fuel filler door is completely unresponsive, and I have the same error messages showing up. Good to know about the repair costs. Will schedule a workshop visit since this seems to need professional attention.

The symptoms you describe are nearly identical to what I experienced, especially with the failure occurring during wet weather. My fuel flap issue also appeared suddenly during rain, which often indicates water damage to the electric actuator. Since your manual release cable is also not working and theres no clicking sound, this strongly suggests a complete lock actuator failure rather than just an electrical connection issue. In my case, moisture had corroded the actuator internals beyond repair. One thing I learned from my repair, make sure the workshop checks the wiring harness near the fuel filler area. Mine had some minor insulation damage that could have contributed to the failure. The replacement lock actuator came with updated seals to better protect against water intrusion. Most common key fob functions using the central locking system run on separate circuits, which explains why those still work normally in both our cases. Based on your service history and similar symptoms, replacing the complete actuator assembly is likely the most reliable fix. The 210 Euro repair cost I mentioned included the updated part design that should be more resistant to moisture damage.

Thanks for all the info and confirming the similarities with your experience. The timing with the rainstorm and lack of any clicking sound really points to the electric actuator being the problem, just like in your case. Will book the repair next week. The 210 Euro cost seems reasonable considering it includes the improved moisture-resistant parts. Good tip about having them check the wiring harness near the fuel filler area, will make sure to mention that. For now, I will carry some extra fuel since I managed to fill up before the lock actuator completely failed. Getting this fixed properly seems like the only real solution, especially since both the electronic release and manual cable release are not working. Really helpful to hear from someone who dealt with the exact same electrical fault. Being stuck without fuel access is definitely not ideal, but at least I know what to expect for the repair now.