RS6 Radiator Fan Failure Causing Dangerous Overheating

I had a similar issue with my 2019 RS7 last summer. As someone with some basic car maintenance experience, I first noticed the engine cooling problems during longer drives. The engine overheating symptoms matched yours exactly, the car radiator fan wasnt engaging properly when temperatures climbed. Initially thought it was the thermal switch, but the workshop diagnostic revealed a faulty speed sensor that was causing incorrect readings, leading to the cooling system malfunction. The repair involved: Full diagnostic scan, Speed sensor replacement, Testing of the car radiator fan operation, Verification of proper engine cooling function Total cost was 250 Euro including parts and labor. The repair resolved all symptoms, including the check engine light. Before suggesting specific solutions, could you provide: Current mileage, Any unusual sounds from the engine bay, Temperature gauge behavior (gradual rise or sudden spikes), Recent maintenance history, Any modifications to the cooling system This information would help determine if your issue matches what I experienced or if its something different in your cooling system setup.

Thanks for checking. My RS6 has 26759 KM and just had its annual service last month. The temperature gauge shows sudden spikes, especially during city driving. No unusual sounds coming from the engine bay, and everything was fine until the car overheating issues started last week. The fan blade movement seems inconsistent, sometimes it engages late, other times not at all. The temperature control issues are most noticeable when idling. During the recent service, they did a standard check of the engine cooling system but found no issues. The car radiator looked clean and properly maintained according to the service report. No modifications have been made to any cooling components.

Based on your description, this sounds remarkably similar to what I experienced with my RS7. The inconsistent fan blade movement combined with temperature spikes during idle strongly suggests a fan motor issue rather than a sensor problem like in my case. The late engagement pattern of your cooling fan is a telltale sign that the fan motor might be failing intermittently. In my experience with similar systems, when the car radiator fan shows this type of behavior, replacing just the sensor or switch rarely resolves the core issue. Since your cooling system was recently checked and the radiator is clean, I would focus on: 1. Testing the fan motor resistance values 2. Checking the cooling fan relay 3. Verifying power supply to the fan assembly When my fan motor eventually failed completely, the replacement cost was 420 Euro including labor. The temperature control improved immediately after the repair, and the check engine light cleared once the new fan motor was properly communicating with the system. Given your low mileage, this might be covered under warranty. Worth checking before proceeding with any repairs.

Thank you for the detailed feedback. Those diagnostic steps make a lot of sense, especially checking the fan motor resistance values. The symptoms you described from your RS7 match my situation perfectly. I will have the workshop focus specifically on testing the cooling fan motor and relay system since the fan noise and engagement patterns seem to be the core issue. I just checked my warranty documents and thankfully this should be covered since Im well under the mileage limit. Will book it in next week and have them run those specific tests on the engine cooling components. The thermal switch testing can be part of their diagnostic process, but based on the inconsistent fan engagement, I agree the fan motor is the more likely culprit. Will update once I get the results back from the workshop. Really helpful to know the typical repair costs as well, even though mine should be under warranty. At least I know what to expect if similar cooling system issues pop up after the warranty period.