VW Virtus Coolant Mystery: Hidden Leaks Explained

As someone with some experience working on VWs, I had a similar issue with my 2018 VW Polo with the same engine configuration. The coolant level warning and engine light also kept appearing despite regular coolant top-ups. After a thorough inspection, the workshop found the issue was related to a faulty wiring connection to the coolant level sensor in the coolant reservoir. The sensor was giving incorrect readings due to a damaged cable. The repair involved replacing the wiring harness and checking the cooling system for any actual leaks. The total cost was 95€ including diagnostic work and parts. While the radiator fluid level was actually fine, the faulty sensor kept triggering warnings. They also performed a complete cooling system pressure test to rule out any real leaks in the radiator cap or elsewhere. To better assist with your case, could you share: Current mileage on your Virtus, Whether you notice the cooling fan behavior changing, If the engine temperature gauge shows any abnormal readings, When you last had a full coolant system service This information would help determine if your issue matches what I experienced or if there might be different underlying causes like head gasket problems that need addressing.

Thanks for the response. My mileage is currently at 125351km. Just had it serviced last month where they did a full inspection but didnt spot any issues with the cooling system at that time. The cooling fan seems to run more frequently than before, even when the engine isnt very hot. The temperature gauge stays in the normal range but occasionally fluctuates slightly. I can hear a gurgling sound from the coolant reservoir area when accelerating, which makes me think there might be air pockets in the system. I will get them to check the sensor wiring like in your case, but honestly Im worried its something more serious since Im actually losing coolant. When they pressure test the system, what specific areas should they focus on to find potential coolant leaks?

Thanks for providing those details. The symptoms you describe with your Virtus are actually quite different from what I experienced with my sensor issue, especially the actual coolant loss and gurgling sounds. The frequent fan operation combined with gurgling noises strongly suggests trapped air in the cooling system. This often happens when the water pump starts failing, which is a known weak point in these engines at around 120000km. In my case, they performed a pressure test focusing on: Water pump seals and mounting, Radiator fluid connections at top and bottom, Coolant reservoir cap seal, Thermostat housing gaskets A failing water pump can cause air pockets to form, leading to those gurgling sounds you hear. The repair cost for my water pump replacement was around 380€ including parts, labor and a complete cooling system flush. Have them pay special attention to the water pump area during pressure testing. Look for weeping or crusty residue around the pump housing, which indicates a slow coolant leak. The increased fan activity typically happens when air pockets reduce cooling efficiency, forcing the system to compensate. Based on your mileage and symptoms, addressing this sooner rather than later would be wise to prevent potential overheating issues.

My engine temperature is still normal but Im getting increasingly concerned about the coolant issue. I took it to the shop today and they confirmed coolant is definitely leaking from the water pump area, exactly where you mentioned to check. They found crusty residue around the pump housing and some weeping during the pressure test. The mechanic also noticed air pockets in the system when bleeding it. Their quote for replacing the water pump, doing a cooling system flush, and testing for any other potential coolant leaks came to 425€. Given the symptoms match what you described and the mileage on my car, Im going ahead with the repair next week. Better to fix the water pump now than risk engine overheating issues down the road. Really appreciate you pointing me in the right direction, saved me time in diagnosing the problem. Will update once the repair is done to confirm if this resolves all the issues with the cooling system and those gurgling noises from the coolant reservoir.