VW Golf Hybrid Battery Drain Causing System Failures

Had a very similar issue with my 2016 VW Passat Hybrid. The vehicle battery problems started with the same symptoms, weak lights, error messages, and starting issues. After some basic troubleshooting like checking battery voltage, it became clear something was draining the battery beyond normal. The workshop diagnosed a faulty battery sensor, which was causing incorrect readings and leading to battery drain issues. The repair cost was 315€ including parts and labor. Since fixing the sensor, all electrical systems have been working perfectly and the low battery warnings disappeared. Based on my experience with hybrid systems, this sounds very similar to your situation. However, to provide more specific guidance, could you share: Has the check engine light come on? Which specific error codes are showing? How old is the current battery? Have you noticed if the battery drain occurs more when parked or while driving? The battery charging system in hybrids is quite complex, and while symptoms often look like a simple battery issue, the root cause can be sensors, control modules, or wiring. Getting those details would help narrow down if your problem matches what I experienced with the sensor failure.

Thanks for the detailed reply. My car had its latest service at 90000km just 2 months ago. To answer your questions: The check engine light flickers intermittently, and the error codes point to battery system faults (P0A80 and P0A7F). The battery is original from 2018, and the battery drain seems worse after the car sits overnight. The battery terminals appear clean but there is some white residue building up. A voltage test showed only 11.2V when the car was off, suggesting significant battery failure or continuous battery drain. Would it make sense to first try a battery replacement, or should I skip straight to having the sensor system checked given the similarity to your case? The battery charging system seems to be struggling, and Im concerned about potential damage to other components if I keep driving it in this state.

Thanks for those additional details about your Golf Hybrid. Those symptoms match exactly what I experienced, but your voltage reading at 11.2V is even lower than what I saw in my Passat (mine was at 11.8V). The white residue on your battery terminals is a clear sign of battery corrosion, and combined with the original 2018 battery, this strongly suggests your vehicle battery is at the end of its life. However, the error codes you mentioned (P0A80 and P0A7F) are specifically related to the hybrid battery system monitoring, just like in my case. Given my experience with the exact same scenario, I would recommend: 1. Get a professional battery test done to rule out a simple vehicle battery failure 2. Have the sensor system checked immediately, continuing to drive with those error codes risks damaging the hybrid system 3. Clean the battery terminals to eliminate any connection issues When my sensor was faulty, it caused a continuous battery drain that ultimately weakened my original battery. The repair shop found that fixing the sensor alone wasnt enough, I also needed a new battery since the old one had been deeply discharged too many times. The entire repair for me included: Battery sensor replacement: 315€, New battery: 180€, System recalibration: 90€ The battery drain issues completely resolved after addressing both the sensor and battery. Given how similar our cases are, you might be looking at comparable repairs.

Based on the battery terminal corrosion and sensor similarities to your case, I really appreciate the detailed breakdown of your repair experience. Those P0A80 and P0A7F codes definitely point to sensor-related issues rather than just a basic dead battery situation. Looking at the cost breakdown you shared (585€ total), this actually seems reasonable given the electrical system complexities in these hybrids. Your suggestion to handle both the sensor and battery replacement makes sense, no point fixing one while leaving the other compromised. I think Ill schedule a diagnostic at the shop this week. The battery drain getting worse overnight plus the low voltage reading of 11.2V suggests this needs addressing soon before it potentially causes more damage. Will make sure they check both the battery terminals and sensor system thoroughly. Thank you for walking through your repair process. Its helpful knowing someone else dealt with and successfully resolved these same hybrid electrical issues. Ill update once I get the full diagnosis and repair completed.