RS7 Transmission Grind & Limp Mode with Oil Issues

Had similar symptoms on my 2020 RS5 last winter. The initial diagnosis pointed to transmission issues, but the root cause was actually the transmission pressure sensor and its wiring harness. The grinding noise during shifts and limp mode engagement are typical signs when the transmission control module receives incorrect pressure readings. The pressure sensor connector had corrosion and a loose pin, causing intermittent signal issues. This triggered the safety protocol in the transmission control unit, forcing it into limp mode. A proper leak detection test showed no actual transmission or radiator problems. The repair involved replacing the transmission pressure sensor assembly and repairing the wiring harness connection. This was a moderate repair that required specialized diagnostic equipment to properly identify. Your symptoms match this scenario perfectly, unusual engagement of limp mode with normal operation in between suggests an electrical rather than mechanical issue. I would strongly recommend getting a second opinion from a shop specializing in Audi transmissions. The combination of check engine light, transmission warning, and grinding sounds might seem severe, but could be resolved without major transmission work if the pressure sensor is the culprit.

Thanks for sharing your experience with the RS5. This is remarkably similar to what I went through with my RS7 last month. The radiator coolant system ended up being completely fine, and like your case, it was the transmission pressure sensor causing all the drama. The car overheating warnings were actually false readings from the faulty sensor. Would you mind sharing what the total repair cost was in your case? I am curious if it was in the same range as what I paid. Also, has everything been working perfectly since the fix, or have you noticed any other transmission-related issues?

Thanks for the follow-up. After seeing a certified mechanic, my RS5 issue was indeed fixed by addressing the faulty radiator oil pressure sensor. The repair cost came to 95 Euro, which covered fixing the defective cable and plug connection. Much more reasonable than initially feared. Since the repair, the transmission has been shifting smoothly with no grinding sounds or warning lights. The cooling system is functioning normally, and the pressure gauge readings are now accurate and stable. It was a relief to avoid a major transmission overhaul. The mechanic confirmed what we discussed, these symptoms often point to sensor or electrical issues rather than mechanical transmission problems. A proper diagnosis with specialized equipment was key to identifying the exact problem and avoiding unnecessary repairs. For anyone else facing similar issues, getting accurate pressure readings through proper diagnostics is crucial before assuming the worst about transmission problems.

Thanks for the input. Just wanted to share how my situation got resolved. After getting a second opinion, I took my RS7 to a specialized transmission shop. The mechanic immediately spotted the issue using their diagnostic tools and found the pressure sensor giving false readings, causing the transmission to act up. The repair was straightforward, they replaced the faulty sensor and fixed some corroded wiring. Total bill came to 780 Euro, including diagnostic time. Much better than the 3000 Euro estimate I got for a supposed radiator repair at the first shop. The car has been running perfectly for the past 2 weeks. No more grinding sounds, no more transmission warnings, and the car overheating alerts have completely stopped. The cooling system is working as it should, and the transmission shifts are butter smooth again. This experience taught me to always get a second opinion, especially when dealing with complex transmission issues. What seemed like a major problem turned out to be a relatively simple sensor fix.