S6 Torque Converter Issues: Grinding and Gear Slippage

I had a very similar issue with my 2012 S7, and with some experience working on cars, I knew this needed professional attention when the transmission started showing those exact symptoms. The lock-up clutch problem in the automatic gearbox turned out to be caused by a defective torque converter. My symptoms matched yours exactly, rough shifting, grinding sounds during gear changes, and the dreaded transmission warning light. The engine surge during acceleration was particularly concerning. The workshop did a complete diagnostic scan first, then confirmed the auto transmission converter was failing. The entire repair, including parts and labor, cost me 2120 Euro. They had to remove the transmission to replace the torque converter assembly. The whole process took about 4 days. To provide more specific advice for your situation, could you share: Current mileage on your S6? When did the symptoms first appear? Have you noticed any transmission fluid leaks? Does the problem get worse when the engine is hot? Any unusual sounds when shifting from park to drive? The diagnostic process is crucial with automatic gearbox issues, as similar symptoms can sometimes point to different root causes.

Just had my 27480 KM service done last month. These transmission issues started shortly after. The clutch problem seems worse when the car is fully warmed up, and yes, there is a distinct clunk when shifting from park to drive. My mechanic initially suspected solenoid issues, but given the similarity to your experience with the torque converter, I will have them investigate that route. The repair cost estimate is helpful, gives me a ballpark of what to expect. Have not noticed any fluid leaks under the car yet. The rough shifting seems most pronounced during the first few gears.

Thanks for providing those additional details. The symptoms you describe, especially the worsening performance when warm and the clunk from park to drive, strongly align with my torque converter failure experience. The timing after your service is noteworthy, though likely coincidental. The auto transmission symptoms you describe match my case precisely. When my torque converter started failing, the initial gear engagement was particularly rough, just as you mention. The transmission repair specialist explained that the lock-up clutch deterioration often manifests first in lower gears before affecting the entire gear range. Your lack of fluid leaks is actually similar to my situation, my torque converter fault occurred without any external leakage. The engine surge and transmission performance issues were the main indicators. Since your mileage is relatively low at 27480 KM, you might want to check if any warranty coverage still applies. My repair costs could have been notably higher if I had delayed addressing the converter fault, as continued operation risked additional transmission damage. The solenoid theory your mechanic suggested is worth investigating, but given the pattern of symptoms, especially the warm engine performance issues, the torque converter is likely the culprit. Would recommend getting a complete transmission diagnostic to confirm.

Given all the details shared, I will definitely pursue the torque converter investigation rather than just the solenoid check. The automatic transmission symptoms match too closely to ignore, especially the worsening performance when warm and that distinct clunk sound from park to drive. The repair cost range is helpful for budgeting, will set aside around 2500 Euro to be safe. Planning to take it to the shop next week for a full diagnostic scan of the automatic gearbox. The clutch problem seems too similar to the other case to be coincidental. While the low mileage is frustrating for such a major issue, I would rather address it now before risking additional transmission damage. Will check about any remaining warranty coverage first, though not too hopeful given the age of the car. At least the lack of fluid leaks suggests the converter failure may be contained to just the torque converter assembly itself. Will update once I get the official diagnosis. Thanks for sharing such detailed information about your similar experience, really helped narrow down the likely cause.