VW Eos Cooling System Symptoms Point to Hidden Issues

I had a similar issue with my 2008 VW Golf GTI. Having worked on several cars before, I can say this kind of thermal management problem needs proper diagnosis. The symptoms you describe match what I experienced. My temperature gauge was giving erratic readings and the engine cooling performance was inconsistent. After a thorough inspection at my workshop, they found a blown fuse controlling the radiator fan circuit. The fix was surprisingly simple, replacing the fuse cost 52€ including diagnostic time. The cooling system is pretty complex though, and similar symptoms can have different causes. A faulty temperature sensor, damaged wiring, or a failing water pump could all cause these issues. While the radiator grille being clear is good, the problem might be electrical rather than mechanical. Could you share: Any engine codes showing up? Does the cooling fan run at all? Are there any coolant leaks visible? What engine variant does your Eos have? This information would help narrow down if your issue matches what I experienced or if you might be dealing with something different in your engine cooling system.

With 37309km and my last service done 3 months ago, I can confirm that the engine fan does cycle on and off, with no visible coolant leaks. The engine code showing is P0118 (Engine Coolant Temperature Circuit High Input). My Eos runs the 2.0L FSI engine. The radiator blockage diagnosis makes sense, but after checking the radiator grille again, all passages seem clear. The car overheating symptoms remain consistent with what you described. Would testing the temperature sensor be a good first step before looking at more complex cooling system repairs? Had the workshop check the fuses as you suggested but they were all intact. Starting to think the temperature sensor itself might be the culprit since the readings are so erratic.

Thanks for those details. The P0118 code definitely points to the temperature sensor circuit, which aligns perfectly with the erratic temperature readings you are seeing. When I had my GTI serviced for similar symptoms, testing the sensor revealed it was sending incorrect signals to the ECU. The cooling system in these 2.0L FSI engines is generally reliable, but the temperature sensors can fail. Since your fuses are good and thermal management seems otherwise normal with the fan cycling, I would focus on the sensor. In my case, the sensor replacement resolved all issues, inconsistent readings, delayed warm-up, and the check engine light. The repair was straightforward: Sensor part cost around 45€, Labor was minimal at 30€, Total fix under 75€ Make sure the workshop uses an OEM sensor, aftermarket ones can cause more problems. Also have them check the wiring harness connection while replacing it, as corrosion at the plug can cause similar symptoms. Just to confirm, is your coolant level staying consistent? While the sensor is likely the issue, its worth verifying no slow leaks are developing in the cooling system that could cause restricted coolant flow.

Thanks for following up on the diagnosis. The P0118 error code matches exactly what my Eos was showing, and with the fuses checked and no visible cooling system issues, I am confident the temperature sensor needs replacement. My coolant level has stayed consistent over the past weeks despite the engine overheating warnings. The radiator grille and general airflow seem fine, which further supports the faulty sensor theory rather than a mechanical cooling problem. Will schedule the sensor replacement this week. The 75€ estimate sounds reasonable compared to what I feared might be wrong. Good tip about insisting on OEM parts, will make sure they do not use aftermarket sensors that could cause more issues down the line. Looks like this could be the simple fix needed rather than a major cooling system overhaul. Will report back after the repair to confirm if it resolved the erratic temperature readings and warning lights.