Audi S8 Transmission Slipping, Expert Help Needed

Recently dealt with similar transmission performance issues on my 2017 Audi RS7. The automatic transmission symptoms matched exactly, erratic shifting, emergency mode activation, and warning lights. The root cause was more serious than just worn hydraulic fluid. Diagnostic tests revealed undervoltage in the transmission control module, which caused the automatic gearbox to malfunction. While a transmission flush might temporarily improve shifting, the underlying electrical issue required attention. The repair involved: Full system diagnostic scan, Transmission control module repair, Replacement of transmission solenoids, Complete transmission flush with OEM hydraulic fluid, Adaptation and recalibration of the transmission control unit The automatic transmission issues were resolved after addressing both the electrical and fluid maintenance aspects. This type of problem typically requires specialized equipment and expertise in high-performance Audi transmissions. Given the mileage on your S8, recommend getting a comprehensive transmission diagnostic before proceeding with any fluid services. The symptoms indicate potential electronic control issues beyond basic maintenance.

Thanks for sharing your experience. That control module issue sounds very similar to what I am experiencing with my S8. The slipping transmission symptoms and error codes match up perfectly. I finally got it diagnosed at a shop but have not proceeded with repairs yet. They also suggested checking the electrical system first before doing any oil replacement in the automatic gearbox. Do you remember roughly how much you paid for the full repair? Also curious if you have had any transmission performance issues since getting it fixed? Want to make sure I budget appropriately and choose a shop that will properly resolve it the first time.

After addressing the electrical system and getting the automatic transmission serviced, I have not experienced any further transmission performance issues. The undervoltage problem was completely resolved, cost me 240 Euro for the electrical repair work. My automatic gearbox has been shifting smoothly ever since. The slipping transmission symptoms disappeared immediately after the fix. It was definitely worth having the electrical system checked first before replacing any transmission fluid. This systematic approach saved money in the long run by targeting the actual root cause. Based on the matching symptoms in your S8, sounds like you are on the right track with the current diagnosis. Just make sure the shop fully tests the transmission control module and electrical system before proceeding with any other repairs. The total repair costs will likely be similar given it is the same transmission family. A proper fix should restore normal automatic gearbox operation and prevent any recurring transmission performance issues.

Thanks everyone for the detailed feedback. I wanted to provide a quick update on my S8 transmission situation. Finally took it to a certified transmission specialist last week. The diagnostic confirmed a faulty control module causing the slipping transmission symptoms. Total bill came to 290 Euro for the electrical repair and transmission flush with fresh fluid. The automatic gearbox is now shifting perfectly again, no more warning lights or emergency mode. The transmission performance feels like new after addressing both the electrical and hydraulic components. Really glad I found a shop willing to properly diagnose before jumping straight to costly repairs. Their systematic approach saved me from unnecessarily replacing major transmission components. Will definitely return to them for future transmission maintenance. The whole experience was straightforward and the final cost aligned with what others paid for similar repairs.