RS4 Transmission Control Module Failing, Gears Grinding

Last year my 2010 S5 had similar transmission problems with grinding during shifts and the transmission control module throwing errors. The transmission diagnosis revealed the mechatronic unit was failing, which controls all the electronic shifting functions in these automatic transmissions. The repair required replacing the entire mechatronic unit since individual components cannot be serviced. This is a serious transmission repair that needs specialized equipment and expertise. The gearbox issues you describe, especially the grinding, slipping, and limp mode, match the classic symptoms of a failing mechatronic unit. The mechatronic replacement resolved all the transmission control problems in my case. The paddle shifters worked properly again and the harsh shifting completely disappeared. This is not a repair that can be postponed, as continued driving risks permanent damage to the transmission internals. For proper diagnosis, the workshop will need diagnostic equipment that can read the transmission control data. Look for a shop specialized in these transmissions, as general mechanics often lack the specific expertise needed for this repair.

Thanks for sharing your experience with the mechatronic unit. I also had my RS4 go through something very similar, TCM errors on the car computer and terrible shifting response. Having these transmission problems fixed was crucial since I use the car daily. Do you remember roughly what you paid for the full repair? Also curious if any other automotive ECU or electronic issues have popped up since getting it fixed? The transmission diagnosis can sometimes reveal other underlying problems that might need attention.

Thanks for asking about the costs. Since having my S5 repaired, the transmission has been working flawlessly with no additional transmission control issues. The automotive ECU readings have been stable, and I havent experienced any electronic problems. The total cost for fixing the defective transmission control unit came to 1000 Euro, which included the diagnostic work and labor. While it was a significant expense, the investment was worth it considering how smoothly the transmission operates now. The grinding and slipping between gears is completely gone, and the paddle shifters respond instantly. The specialized transmission repair shop did a thorough job testing all related control modules to ensure there were no underlying issues. If your symptoms are similar to what I experienced, addressing the transmission problems early will help prevent more extensive damage that could be far more costly to repair.

Updated situation, taking it to a reputable transmission specialist and getting it properly diagnosed was definitely the right call. The mechanic found exactly what was described, a failing mechatronic unit causing the transmission problems. The full repair cost came to 2800 Euro including parts, labor and diagnostic work. More than initially hoped, but worth every cent considering how the car drives now. The grinding noise is completely gone, gear changes are smooth again and the paddle shifters work perfectly. The car computer shows no more transmission control module errors and the electronic issues have been fully resolved. The shop also did a full transmission fluid change and updated the car computer software while they had it open. It has been running great for the past month with zero transmission problems. My advice to anyone facing similar gearbox issues, dont wait around hoping it will fix itself. Get it to a qualified transmission specialist before the problem gets worse and causes additional damage. The repair cost might seem high but its far cheaper than replacing the entire transmission later.