Audi Q7 Trans Issues Linked to Radiator Pressure

I faced a similar situation with my 2009 Audi Q5 diesel last year. I have some experience working on cars, mainly basic maintenance and troubleshooting. The symptoms you describe match what I experienced, particularly the transmission behavior and warning lights. After investigating, it turned out the cable connection to the transmission oil pressure sensor was damaged, causing erratic readings and putting the system in limp mode. The mechanic performed a thorough cooling system inspection and leak detection test first, since transmission issues can often be linked to the oil cooler and radiator system. The pressure gauge readings helped identify that the transmission itself was fine, but the sensor connection was the culprit. The repair involved replacing the wiring connector and checking the transmission fluid levels. Total cost was 95 Euro for parts and labor. Before suggesting more specific solutions, could you share: Current mileage on your Q7, When was the last transmission service done, Are there any coolant or oil leaks visible, Does the issue happen more when the engine is cold or warm This information would help determine if your case is similar to what I experienced or if its something else in the transmission system.

Had my routine service just last month at 19745 KM. After checking the cooling fan operation and doing a pressure gauge test, the mechanic found the transmission fluid was mixing with coolant through a cracked oil cooler. This was causing similar symptoms to what you described. The leak detection showed transmission fluid contamination in the cooling system. Once the oil cooler was replaced and new fluids added, all warning lights cleared and the transmission returned to normal operation. Make sure your mechanic checks for coolant leaks and cross-contamination, as this can damage the transmission if left unchecked. The total repair came to 850 Euro in my case.

That definitely confirms what I suspected after my own experience with the oil cooler failure. The symptoms are almost identical, and the car overheating issues that follow are a clear indicator. After my repair, I learned that regular cooling system maintenance is crucial for preventing these expensive failures. The mechanic explained that the transmission oil cooler in these models can develop micro-cracks that slowly worsen over time. When I had mine fixed, the shop also recommended flushing the radiator and replacing all cooling system fluids to prevent any leftover contaminated fluid from causing future problems. For reference, my repair bill was higher at 1100 Euro because I also needed the radiator repair due to some damage from the contaminated fluid. The leak detection test showed multiple points of concern in my case. One crucial tip: make sure they pressure test the entire cooling system after the repair. In my case, they found additional small leaks during the final inspection that could have caused problems later. Its good you caught this early at 19745 KM. Mine failed at 125000 KM and caused more extensive damage to the transmission system.

Thanks for sharing your experience. After comparing the costs and repair procedures, I feel much better about catching my issue early. The mechanic showed me how the cooling system inspection and pressure test revealed the exact problem, saving time on unnecessary diagnostics. The cross-contamination between transmission fluid and coolant through the cracked oil cooler could have caused much more damage if left unchecked. My repair bill of 850 Euro seems reasonable compared to cases where the transmission system suffered extensive damage. I am particularly grateful for the tip about ensuring thorough pressure testing after the repair. My mechanic did exactly that and verified no additional coolant leaks existed. The cooling fan is working properly now, and all transmission-related warning lights have cleared. For anyone else facing similar symptoms, I recommend getting the cooling system checked right away, especially the transmission oil cooler connections. Early detection of these issues can prevent costly transmission repairs down the line. My car shifts smoothly now and operates at normal temperatures without any warning lights.