RSQ3 Transmission Issues Point to Faulty Temp Sensor

I had a similar issue with my Q3 2.0T (2013) and can share my experience as someone with moderate experience working on cars. The symptoms you describe match exactly what I encountered, rough shifting, grinding, and the automatic transmission eventually going into limp mode. The transmission warning light was definitely concerning. After checking the transmission oil level, the workshop discovered it was significantly low, which caused overheating problems and triggered the temperature sensor warnings. The low oil level was stressing the transmission components and causing the erratic behavior. The repair involved: Complete transmission oil flush and refill, Replacement of the transmission temperature sensor, Diagnostic system reset, Test drive to confirm proper operation Total cost was 365 Euro including parts and labor. The repair completely resolved the shifting issues and warning lights. Before suggesting specific fixes, could you share: Current mileage on your vehicle? When was the last transmission service performed? Are you noticing any transmission fluid leaks under the car? Does the problem get worse when the engine is hot? This information would help determine if your issue is similar and requires the same solution.

Thanks for the detailed response. The mileage is 168951 KM and the last service was just 2 months ago where they did a basic inspection but no transmission work. To answer your questions: No visible leaks under the car, but the transmission problems definitely worsen after driving for about 20 minutes when everything heats up. The shifting gets particularly rough during highway driving. Your description of the overheating problems matches what I am experiencing. The transmission sensor symptoms are nearly identical. With the cost being reasonable at 365 Euro, I might take it to the workshop and have them check the temperature sensor first. Would you recommend having them do a complete transmission oil flush while they are at it, even though the car was recently serviced?

Based on your symptoms getting worse with heat and the similar patterns we both experienced with our Q3s, I definitely recommend having both the temperature sensor checked and the transmission oil flushed simultaneously. Even though your car was recently serviced, they likely only performed a basic inspection without checking the transmission fluid quality or the gearbox sensor functionality. My mechanic explained that transmission problems often start with the temperature sensor failing, which then leads to incorrect readings and improper gear shifting patterns. When my automatic transmission was repaired, doing both jobs together saved on labor costs since they already had to access the same areas. The fresh fluid made a noticeable difference in shifting smoothness, and replacing the faulty temperature sensor prevented further overheating problems. The complete flush also helps identify if there are any underlying issues, in my case, they found small metal particles in the old fluid that indicated early wear. Catching this early prevented more expensive transmission repairs down the road. Since your mileage is actually higher than mine was during the repair, a full transmission service alongside the sensor replacement would be a smart preventive measure to protect your gearbox.

Since you answered my questions and shared your experience with such a similar issue, I will definitely proceed with both the transmission oil flush and sensor replacement. The fact that the problems worsen after 20 minutes of driving really seems to confirm the temperature sensor theory. My transmission issues match your previous situation almost exactly, from the rough gear shifting to the warning lights and emergency mode. Given the high mileage on my car and the fact that the last service didnt include transmission work, getting both jobs done together makes perfect sense. Not only will it likely fix the current problems, but it could also prevent more serious automatic transmission damage. I will schedule an appointment with a workshop right away and specifically request they check the transmission oil temperature sensor and do a complete fluid flush. The 365 Euro cost seems very reasonable considering the potential damage that could occur if left unaddressed. Will update once the repair is completed to confirm if this resolved my transmission issues.