A5 Transmission Crisis: TCM Failure Warning Signs

Having some experience with transmission issues, I can relate to your A5 problems. I had very similar symptoms with my 2014 A4 which also has an automatic gearbox. The symptoms you describe match exactly what I experienced, especially the transmission diagnosis showing multiple fault codes. Initially, I was worried it might be mechanical transmission damage, but after proper diagnosis, the workshop confirmed it was the transmission control unit that was defective. The car computer was showing multiple errors related to the gearbox issues. The repair involved replacing the control module and reprogramming the new unit. Total cost was around 1000 Euro, including parts and labor. After the fix, all transmission-related problems disappeared completely, no more rough shifting, limp mode, or error codes. Before offering more specific advice for your case, could you share: Current mileage, When did symptoms first appear, Which specific fault codes were stored, Have you noticed any fluid leaks, Does the problem occur more when the engine is cold or warm This information would help determine if your issue is identical to what I experienced with my A4 or if there might be other factors to consider.

Thanks for the input. My A5 is in need of its annual service and has 117337 KM on the clock. I had the transmission control module checked at a specialized gearbox repair shop. The diagnosis showed multiple electronic faults in the transmission control system, similar to what was mentioned. The automatic gearbox issues started getting worse over the past month, especially during cold starts. No fluid leaks visible, but the transmission warning light keeps coming on after about 10 minutes of driving. I will get more detailed fault codes tomorrow and share them here. Based on the repair costs mentioned, this seems like a reasonable fix if it completely resolves the gearbox issues. Will update once I have more information from the specialist.

Thanks for the update. Your A5 symptoms continue to sound nearly identical to what I dealt with on my A4, especially the cold start issues and transmission warning light behavior. The mileage is also in a similar range where these electronic issues commonly develop. The gradual worsening of automatic gearbox problems over weeks matches the typical failure pattern of the transmission control unit. In my case, the warning light also started appearing intermittently before becoming constant. My repair shop first performed a complete transmission diagnosis which revealed multiple electronic faults. The gearbox issues were definitely linked to the control module rather than mechanical wear. Getting those detailed fault codes will help confirm if your case matches the same pattern. The quoted repair costs seem to be in line with what I paid for the transmission control unit replacement. Just make sure the shop includes proper programming and adaptation of the new unit in their quote, as this is essential for resolving the electronic issues completely. Would recommend having them check the transmission fluid level and condition while they have it in, even though you dont see leaks. My shop did this as a precaution during the control module replacement.

Based on all the responses, I can now conclude: Thank you all for sharing your similar experiences. After getting the transmission diagnosis completed today, the fault codes confirmed multiple electronic issues with the control module, exactly matching what others described. The transmission problems are indeed very similar to the A4 case mentioned. The repair shop found P0700 and P0730 among other transmission-related codes. They performed a complete system check and confirmed the automatic gearbox itself appears mechanically sound, with the transmission control unit being the primary issue. Got a final quote of 1200 Euro for the complete repair, including: New transmission control module, Programming and adaptation, Full fluid check and top-up, Post-repair diagnostic scan Given the consistent feedback about successful repairs in similar cases, I have scheduled the work for next week. Will post a follow-up about how the car computer and transmission problems respond to the new control unit. Thanks again for helping confirm this was indeed an electronic rather than mechanical transmission issue. The repair costs seem reasonable considering the alternative of major transmission repairs.