VW Eos Coolant Leak Linked to Control Module Issues

Had nearly identical issues on a 2015 VW Golf TSI. The diagnostic trouble code pointed to a control unit malfunction affecting the cooling system. The root cause was a wiring issue between the engine control module and coolant temperature sensors. Main symptoms matched yours: Engine overheating, Coolant leaks, Check engine light, System pressure problems The repair required: Full diagnostic scan revealing communication fault in the CAN bus network, Replacement of corroded wiring harness connectors, Recalibration of the engine control unit, Pressure testing of the entire cooling system This was a serious issue requiring specialized diagnostic equipment. The communication fault between modules caused the cooling system to malfunction, leading to pressure buildup and coolant loss. Standard mechanical checks alone would not have identified the electrical root cause. Recommend having the CAN bus network tested before replacing mechanical components. A proper diagnosis should include checking the wiring connections at the coolant temperature sensors and engine control module. The repair took several days due to the complex nature of the electrical fault finding process.

Thanks for helping with my VW Eos problem. My connectivity issue turned out to be exactly what you described, faulty wiring between the control unit and temperature sensors causing all those cooling system problems. The communication fault was tricky to diagnose but definitely worth fixing properly. Just wondering, do you remember roughly what it cost you to get everything sorted? Also, has your car been running fine since the repair or have you noticed any other data link issues popping up? Would really appreciate knowing if its been a lasting fix.

After my VW repair, the car diagnostics showed the control unit communication error was completely resolved. The mechanic traced it to a damaged cable connection which was causing the software glitch, exactly like your case. Total cost was 95€ for replacing the faulty connector and running final tests. Been driving it for 8 months now without any new wiring issues or connectivity problems. The cooling system works perfectly, and all sensor readings are normal. Having the right diagnostic equipment to find that initial communication fault made all the difference in getting a proper fix rather than just treating symptoms. My recommendation is to keep an eye on the coolant temperature readings for the next few weeks just to be sure everything stays stable. But based on my experience, once these electrical gremlins are properly sorted, they tend to stay fixed.

Thanks for the advice. Wanted to share how my repair turned out. Found a shop specializing in VW electrical diagnostics and they immediately spotted the connectivity issue in the CAN bus network. The wiring harness near the temperature sensor was damaged, causing all those cooling system problems. Total repair came to 850€ including: Complete diagnostic scan, Wiring harness replacement, Control module recalibration, New coolant temperature sensor, System pressure test Been driving for 2 weeks now and everything works perfectly. No more check engine lights, no overheating, and no coolant leaks. The diagnostic trouble codes are all cleared and staying that way. Was worth finding a shop with proper diagnostic equipment rather than trying unusual fixes. Lesson learned about getting the electrical systems properly checked before assuming mechanical problems. Really glad to have this sorted properly after that first bad repair experience.