Audi A8 Trans Issues Linked to Cooling System Failure

A similar issue occurred on my Audi A6 3.0 TDI from 2014. Having some experience with transmission-related problems, I recognize these symptoms. The leak detection process revealed a faulty connection at the pressure sensor wiring harness. Car overheating was initially suspected, but the workshop found no coolant leak. The transmission was going into emergency mode due to incorrect pressure readings from the sensor. The fix was straightforward, replacing the wiring harness and connector to the pressure sensor. Total cost was 95 Euro for parts and labor. Since the repair, the transmission has worked flawlessly with no more warning lights or emergency mode incidents. To provide more specific advice for your case, could you share: Current mileage, Whether any transmission fluid service has been done recently, If the car overheats or loses coolant, Any transmission fluid leaks visible under the car, Specific error codes from diagnostic scan These details would help determine if your issue matches what I experienced or if further investigation is needed, particularly regarding the oil cooler and cooling system components.

My mileage is currently at 135773 KM and had the last service done at 130000 KM. Just got some diagnostic scan results back and double checked a few things. The radiator coolant levels look normal and the cooling fan operates as expected. After further inspection, the transmission oil cooler shows signs of corrosion near the connection points. The workshop quoted 450 Euro for a complete replacement of the oil cooler assembly, including labor. Before proceeding, Id like to know if this pricing seems reasonable and whether fixing just the connections might be a viable alternative to replacing the entire unit.

This matches my experience exactly. After discovering similar corrosion on my A6s oil cooler connections, I initially considered just repairing the connection points. However, when the cooling system was pressure tested, the workshop found microscopic cracks in the oil cooler that weren't immediately visible. The 450 Euro quote aligns with what I paid (mine was 480 Euro). The full replacement proved to be the right choice, as it resolved both the transmission issues and prevented potential coolant contamination. The radiator coolant might look fine now, but corrosion at connection points often indicates internal wear that could suddenly worsen. Using a pressure gauge test confirmed that even with normal coolant levels, the system wasnt maintaining proper pressure due to the deteriorated oil cooler. This affected transmission performance since proper cooling is crucial for transmission fluid operation. Some tips from my repair experience: Ensure they flush the cooling system completely, Check transmission fluid quality after repair, Validate pressure readings post-repair, Request inspection of surrounding hoses while system is apart Attempting to fix just the connections would likely be a temporary solution and could lead to more expensive repairs later.

Thanks for the detailed information about your experience with a similar oil cooler replacement. After reviewing my diagnostic scan results and your feedback, I feel more confident about proceeding with the complete replacement rather than just fixing the connections. The radiator coolant pressure test my workshop performed confirms your point about microscopic cracks. While my cooling system shows no obvious leaks, the pressure readings are indeed fluctuating more than they should. Combined with the visible corrosion around the oil cooler connections, this explains the transmission behavior. I scheduled the repair for next week. The 450 Euro price seems fair based on your experience and current market rates. I will make sure they follow your suggested checklist, especially the cooling system flush and pressure validation after installation. One question remains, did you notice any improvement in transmission performance immediately after the repair, or did it take some time for the system to adjust?