VW T-Roc Fan Failure After Cooling System Service

Had a similar issue with my 2020 VW Tiguan. The radiator fan stopped working after routine maintenance, causing engine temperature spikes. The problem turned out to be a faulty thermal switch that wasnt properly reconnected during the previous cooling system service. The symptoms matched exactly, no fan noise when the engine got hot and the check engine light came on. The thermal switch controls when the radiator fan should activate based on coolant temperature. When it fails or gets disconnected, the fan wont turn on, leading to overheating. This was a serious issue that needed immediate attention since continued overheating could damage the engine. The repair involved testing the cooling system pressure, replacing the thermal switch, and verifying proper fan operation at different temperature thresholds. Given your symptoms and recent mechanic work, have them check the thermal switch connections and fan relay first. The fact that this started after recent cooling system work suggests possible oversight during reassembly rather than a major component failure. Would recommend getting this checked soon, driving with an overheating engine can lead to costly damage.

Thanks for sharing your experience with the thermal switch issue. The symptoms you described match mine completely, especially the fan not activating when the engine cooling system needs it most. This definitely gives me a good starting point when I take it back to the shop. How much did the repair end up costing you? Also curious if youve had any temperature control problems since getting it fixed?

Thanks for asking about the follow-up. The repair worked out perfectly, no more temperature control issues since getting it fixed. The speed sensor was indeed defective and needed replacement, which cost 250€ including labor. The mechanic confirmed the fan motor now activates properly when the engine cooling system requires it. The radiator fan works flawlessly now at all engine temperatures, and the check engine light hasnt come back on. Regular testing shows the cooling system is maintaining proper temperature levels under all driving conditions. It was definitely worth getting it sorted quickly to prevent any potential engine damage. If your symptoms are similar, you should see comparable results once repaired. Just make sure they thoroughly test the fan blade operation across different temperature ranges after the fix.

I took the car back to the shop today and showed them your suggestions about the thermal switch. They ran a diagnostic and found exactly what you described, the thermal switch was not properly connected during the last service. The fix was straightforward and cost 180€ for the inspection, reconnection and system testing. The fan motor now kicks in properly when needed, and the fan blade spins as it should when the engine temperature rises. No more check engine light or overheating issues. The mechanic admitted their oversight during the previous cooling system maintenance and waived the labor charge. They also performed a complete temperature control test to ensure everything was working correctly at various engine temperatures. This turned out to be a much simpler fix than I feared, thanks to the advice about checking the thermal switch first. The car is running perfectly now with proper engine cooling.