Audi TT Radiator Fan Failure Causes Major Overheating

I had a similar problem with my 2013 Audi TTS. As someone with some experience working on Audis, I first noticed the engine cooling issues during stop-and-go traffic. The radiator fan stayed silent even when the engine temperature was high. After inspection, it turned out the speed sensor was defective, which prevented the thermal switch from properly activating the fan blade assembly. The engine cooling system couldn't function correctly, leading to car overheating. My trusted workshop diagnosed it quickly. The complete repair, including parts and labor, cost me 250 Euro. They had to replace the speed sensor and verify the radiator fan was working properly across all speed ranges. The fix completely resolved the overheating issues, and the cooling system has worked flawlessly since then. Before suggesting more specific solutions, could you share: Does the fan work at all, or is it completely non-functional? Have you noticed any coolant leaks? When exactly did the check engine light appear, before or after the overheating started? What temperature readings are you seeing on the gauge? This information would help determine if your issue is identical to what I experienced.

Latest service was at 24297 KM. The fan motor is completely dead, no response at any temperature. Had my mechanic verify there are no coolant leaks in the system. The check engine light came on right after I first noticed the temperature climbing past normal range. Temperature gauge hits red zone within about 10 minutes of city driving. The fan noise used to be clearly audible when the car was hot, now there is complete silence. I checked the fuses but they all appear fine. Temperature control seems very erratic compared to normal behavior. Really appreciate the detailed info about the speed sensor, will definitely have that checked. Good to know the repair costs were reasonable in your case.

Based on your description, this sounds exactly like the same fan motor failure I dealt with on my TT. The symptoms match perfectly, complete fan silence, rapid temperature rise, and erratic temp control are classic signs. The fact that your fan motor shows zero response points more toward a complete fan motor failure rather than just a speed sensor issue like I initially had. The thermal switch and fan motor work together as part of the engine cooling system, and when either fails, you get these overheating problems. In my case, I was lucky it was just the sensor. Looking at your symptoms, you will likely need a complete radiator fan assembly replacement. The repair should cost around 400-600 Euro including labor, as the fan motor itself is more expensive than just the sensor. Would strongly recommend getting this fixed soon. Running with no functional cooling fan risks serious engine damage, especially during slow driving when there is less airflow through the radiator. Quick tip: Until you can get it repaired, try to avoid stop-and-go traffic and keep the engine speed up to maintain airflow. But really, the car needs proper service to prevent potential engine damage from overheating.

Thanks for the advice on the fan motor assembly. You are probably right about needing the complete unit replaced since there is zero fan noise or activity. I will schedule the repair this week since I cannot risk damaging the engine from constant car overheating. The 400-600 Euro estimate helps set my expectations for the repair cost. The temperature control issues are definitely concerning, especially since I rely on this car for daily commuting with lots of stop-and-go traffic. Will ask them to check both the thermal switch and the entire cooling system while they have it in the shop, just to be thorough. Good to understand the relationship between the fan motor and temperature regulation. At least I can go to the shop with some knowledge about what is likely wrong instead of being completely in the dark about the repair. I will follow your tip about keeping engine speeds up to maintain airflow until I can get it fixed. But you are right, need to get this resolved properly rather than trying workarounds with a faulty cooling system.