VW Golf EV Power Loss Points to High-Voltage System Fault

I had a very similar electrical fault with my 2017 VW e-Up. My experience with EVs is moderate, having owned two electric vehicles over the past 5 years. The symptoms you describe match what I encountered, system malfunction warnings followed by power reduction and complete shutdowns. After multiple diagnostic attempts, my workshop identified a severe battery drain issue caused by a faulty voltage sensor in the high-voltage system. The repair involved: Full diagnostic scan of the battery management system, Replacement of the defective voltage sensor, Recalibration of the battery monitoring system, Testing under load conditions Total cost was 290€ and resolved the shutdown problems completely. No issues since the repair. Before suggesting specific solutions, could you share: Current battery capacity percentage, Any recent charging issues, Exact error codes stored in memory, Temperature conditions when failures occur, Approximate mileage since last service This information would help determine if your issue matches what I experienced or points to a different inverter issue or system component failure.

Just had my service at 126806km and the technician previously ran a full diagnostic. The error codes showed P1234 and P5678, consistently appearing after each shutdown. Battery capacity stays around 85% but drops rapidly during these failures. Issues happen regardless of temperature, even right after a full charge. The charging itself works fine when the car actually accepts power, no warning lights or error messages during charging sessions. But the sudden power losses are getting more frequent, happening 3-4 times on my last longer drive. Each time it requires a complete restart after pulling over. The battery management system is also showing unusual voltage fluctuations according to the OBD readings.

Thanks for those details, actually had nearly identical error codes with my e-Up before the repair. The voltage fluctuations you mention definitely align with the voltage sensor malfunction I experienced. The frequency of your shutdowns matches my issue too, mine started with occasional cuts but quickly progressed to multiple failures per trip. The fact your charging works normally but shows voltage fluctuations during operation points strongly to the same electrical wiring and sensor issues I dealt with. My voltage sensor was misreading the battery state, causing the management system to trigger safety shutdowns. The high-voltage system kept going into protection mode unnecessarily because of incorrect voltage readings. After replacing the faulty sensor and recalibrating the system, those erratic voltage readings completely stopped. Based on these matching symptoms, especially the OBD data showing voltage instability, Id suggest having your workshop specifically check the voltage monitoring components in the high-voltage system. The repair should be similar to what I had done, replacement of the sensor and full system calibration. The good news is that if its the same issue, its a relatively straightforward fix once properly diagnosed. Let us know what the workshop finds, would be helpful to confirm if its indeed the same root cause.

Thanks for the detailed responses. This really helps narrow down the likely cause. The voltage sensor theory makes a lot of sense given how the symptoms match up exactly, especially the voltage fluctuations and system shutdowns becoming more frequent over time. I called my regular workshop and they can check the high-voltage system components next week. Mentioned the potential voltage sensor issue and they agreed its a common failure point that matches the electrical fault pattern. The expected repair cost is around 320€ which seems reasonable based on the previous repair experience shared here. Will update once they diagnose and fix the system malfunction. Really hoping its just the sensor and not a more serious battery or inverter problem. Thanks again for helping point me in the right direction with this, at least now I have a much better idea what to expect at the workshop.