SQ8 Trans Issues: Shift Problems & Limp Mode Alert

Had similar transmission performance issues with my 2018 Audi S6. The symptoms matched exactly, transmission not shifting smoothly and limp mode activation. Initially thought it was just dirty transmission oil, but diagnostic revealed an undervoltage problem affecting the transmission control module. A simple transmission flush would not have fixed this. The issue required professional diagnostic equipment to identify electrical system faults affecting the transmission management. The main problem was a failing voltage regulator that wasnt providing consistent power to the transmission control unit. The repair involved: Full system diagnostic, Replacement of voltage regulator, Reset of transmission control module, Fresh transmission oil and filter change The hydraulic fluid change was done as preventive maintenance, but the core issue was electrical. This was a serious problem that could have led to complete transmission failure if left unaddressed. The car transmission system on modern Audis is heavily dependent on proper voltage supply for optimal operation. Would recommend having a full diagnostic done at a shop with proper Audi-specific equipment rather than assuming its just a fluid issue. These symptoms often indicate more complex electrical problems in the transmission system.

Thanks for sharing your experience. Your situation sounds very similar to what I am dealing with right now. The automatic transmission problems started suddenly in my SQ8, and I was also hoping a simple transmission flush would fix it. Did the complete repair resolve all issues? Just curious about the final cost of fixing everything, the diagnostic, car transmission repairs, and hydraulic fluid replacement. My local repair shop quoted quite a high price and I want to compare. Also wondering if you had any recurring problems after the fix?

Since getting the work done on my S6, the automatic transmission has been working flawlessly. The undervoltage issue was completely resolved after replacing the voltage regulator and performing the system reset. My total repair cost came to 240 Euro, which included the diagnostic work, parts, and labor. They also did a transmission flush while the system was open, though this was more preventative than necessary for fixing the core problem. The automatic gearbox now shifts perfectly, no more warning lights or limp mode episodes. Going on 8 months now with zero transmission problems or electrical issues. The transmission control module is getting proper voltage and everything operates as designed. For your SQ8, I would expect similar repair costs since the symptoms match exactly what I experienced. Just make sure the shop has proper diagnostic equipment for modern transmission systems. A basic transmission flush alone likely wont address what appears to be an electrical issue affecting your transmission performance. In my case, investing in proper repairs from a qualified shop was worth every cent to restore proper automatic transmission function and prevent more expensive damage down the road.

I followed through with getting my SQ8 checked at a specialized transmission shop. Turns out my problem was indeed similar, a faulty voltage regulator causing the slipping transmission issues. The total repair included diagnostic testing, replacing the regulator, and a transmission flush. The whole job cost me 290 Euro, slightly more than expected but worth every cent. The automatic gearbox now shifts perfectly again, and all warning lights are gone. Driving home from the shop felt like having a new car, smooth gear changes and no more limp mode issues. The mechanic explained that the hydraulic fluid change was necessary since they had the system open, though the electrical issue was the main culprit. Really glad I didnt just try a basic transmission flush at my regular shop, as this could have missed the underlying voltage problem. After two weeks of driving, the transmission continues working flawlessly. No warning lights or unusual behavior. Getting it fixed at a shop with proper diagnostic equipment was definitely the right choice.