Bought this 2011 S4 with 130,000km on it for cheap with transmission issues. The radiator had failed and caused coolant to mix into the DCT fluid. Shop said they installed a new radiator and flushed it several times but the clutches were still slipping and the car was not shifting properly. After opening it up, I realized they never bothered to drop the pan and there was still a large amount of milk left in there. I thought maybe I could clean the mech unit thoroughly and get rid of all the contamination, especially the ATF filter which was deteriorating due to the coolant, and it might fix the issues if the clutches weren’t heavily affected. Helped a little bit, but was still far from good. I then sourced a transmission and threw it in the back of my A8 (barely fit) to bring it home. Took about a week to install as it was my first time ever doing something this intensive. I swapped over the TCU from the original transmission into the donor to try and bypass any ODIS coding. Didn’t know if swapping the TCU was gonna work, but both the transmissions were the same production code so I had a lot of hope that it would. Got the car running, did the adaptations and now it’s shifting great! Just thought I’d post this to let people know that a TCU swap is a viable option to not have to deal with the headache of ODIS. Side note: Audi wanted to charge me $1500 for the NUTS AND BOLTS to install the transmission. I sourced them elsewhere…

B8 Transmission Swap (no ODIS!)