Audi A6 Trans Issues: Oil Cooler Sensor Failure Alert

I had almost the exact same issue with my 2011 Audi A4 last year. Having worked on basic car maintenance, I would say I have some experience with repairs, though transmission issues can be quite complex. The symptoms you describe match what I experienced, inconsistent shifting, warning lights, and emergency mode activation. After using a pressure gauge to diagnose the problem, my mechanic found that the pressure sensor connection was faulty, causing incorrect readings and transmission fluid pressure regulation issues. The repair involved replacing the pressure sensor and checking the radiator coolant system, since the oil cooler is connected to the cooling circuit. The total cost was 95 Euro for parts and labor. Since the fix, the transmission has been working perfectly with no recurring issues. For a proper diagnosis, could you share: Current mileage on your A6, When was the last transmission fluid change, Are there any coolant leaks visible, Does the problem occur more when the engine is cold or hot This information would help determine if your issue is identical to what I experienced or if there might be additional factors to consider. Leak detection tests might also be worth doing to ensure there are no other underlying problems with the cooling system.

Last service was done at 20652KM and the mechanic did a complete transmission fluid change. After inspecting the car more closely, I noticed small traces of coolant under the car, which makes me think the problem could be more serious than just a faulty pressure sensor. The cooling fan seems to be running more frequently than usual, and the temperature gauge shows slightly elevated readings. Symptoms definitely get worse when the engine is hot, particularly in stop-and-go traffic. I noticed the car overheating twice last week, which probably indicates a connection between the coolant leak and transmission issues. Based on this, it seems I might be dealing with both a cooling system problem and transmission sensor issues. The radiator repair might need to be prioritized before addressing the transmission symptoms.

Hate to say it, but your symptoms sound more severe than what I dealt with. While my A4 only needed a sensor replacement, your coolant leak and overheating issues suggest a potentially failed oil cooler unit. After seeing the traces of coolant and hearing about the overheating, I strongly recommend getting the cooling system pressure tested first. When my mechanic did the initial leak detection on my car, it helped rule out bigger problems. The cooling fan running constantly is definitely a red flag that wasnt present in my case. The transmission symptoms getting worse with heat makes sense, if the oil cooler is compromised, the transmission fluid isnt being cooled properly. My repair was straightforward since it was just the sensor, but you might be looking at replacing the complete oil cooler assembly. From my experience with cooling system repairs on these models, keep an eye out for: Any mixing of transmission fluid and radiator coolant, Pressure loss in the cooling system, Unusual transmission fluid color or smell Given that your car is already overheating, I would avoid driving it until getting it checked. My repair costs were minimal at 95 Euro, but a full oil cooler replacement will likely run significantly higher.

Thanks for the detailed info and observations. The overheating and coolant leak you described definitely points to more than just a sensor issue. Looking closer at my situation now makes me realize I should address both cooling system and transmission problems together. I called my mechanic to schedule a full diagnostic with a leak detection test. Given the rapid coolant loss and transmission fluid mixing risk, I decided not to drive the car until they can check it. The radiator repair and oil cooler replacement might be expensive, but its better than risking more damage. The frequent cooling fan cycles and temperature spikes in traffic are concerning, especially since they werent happening before the transmission started acting up. My mechanic says a pressure gauge test will confirm if the entire oil cooler needs replacement. I will update once I get the full diagnosis. Right now I am preparing for a potentially bigger repair bill than just a sensor replacement, but at least I caught the coolant leak before any major damage occurred to the transmission.