Nivus TSI Coolant Mysteriously Disappearing Despite Refills

The coolant loss issue combined with check engine light sounds similar to what happened with my 2017 T-Cross 1.0 TSI last year. The symptoms match perfectly, coolant reservoir getting low without visible leaks. After inspection, it turned out the head gasket was failing internally, allowing coolant to enter the combustion chamber in small amounts. This explained why there were no visible leaks under the car. The mechanic found the issue by performing a compression test and using a coolant system pressure tester. Key signs that indicated a serious problem: Gradual coolant loss without external leaks, Slightly sweet smell from exhaust, Small white smoke on cold starts The radiator cap and radiator hoses were also inspected during diagnosis but were functioning properly. This type of internal leak requires immediate attention as it can lead to severe engine overheating if left unchecked. This is typically a major repair job that requires partial engine disassembly. Would strongly recommend having it properly diagnosed at a specialized VAG workshop rather than continuing to top up the coolant.

Thanks for sharing your experience. I faced nearly identical symptoms with my VW last summer. Since replacing the head gasket, I have not lost a single drop of coolant and the check engine light never came back. The cooling fan and radiator fluid circulation are working perfectly now. Have you gotten it fixed yet? Would be good to know what the final cost was in your case and if you encountered any other issues afterwards.

Glad to hear your repair worked out well. Yes, I did get mine fixed, it turned out my issue was actually much simpler than a head gasket problem. The mechanic found a faulty sensor connection was triggering the check engine light and causing incorrect coolant level readings. The coolant leak was traced to a loose cable connection rather than an actual system failure. The total repair cost was 95€ for fixing the connection issue. Since the repair, the coolant level has remained stable and the engine cooling system works perfectly. No engine overheating or warning lights have appeared in the months following the fix. This experience shows why proper diagnosis is crucial, what seemed like potential head gasket failure turned out to be a straightforward electrical fix. The mechanic also checked the radiator hoses and radiator cap during inspection, but these components were all in good condition.

After reading about similar experiences, I took my car to a different mechanic who specializes in VW engines. The diagnostic testing revealed a failing water pump, not the head gasket as initially suspected. They found air pockets in the cooling system caused by the faulty pump. The repair cost 450€ including parts and labor. Since the fix last month, the coolant level has remained stable and the check engine light is gone. The cooling fan cycles normally now and the engine maintains proper temperature. Much better experience than my previous shop visit. This shows how important it is to get an accurate diagnosis rather than just topping up fluids and hoping for the best.