VW Up Electrical Chaos: Alternator vs ECU Battle

I had a very similar electrical issue with my 2013 VW Polo TSI. Having some experience working with basic car electronics, I initially thought it was just a battery problem, but it turned out to be more complex. The symptoms matched yours exactly, multiple system failures, difficult starting, and overvoltage warnings. The power surge issues were causing unusual electrical glitches across different systems. After taking it to a workshop, they performed a complete electrical diagnostic. The testing revealed a failing battery that was causing voltage fluctuations, which then triggered the overvoltage protection systems. The high voltage spikes were indeed putting stress on various electrical components. The solution involved: New battery installation, Full system diagnostic scan, Testing of charging circuit, Verification of alternator output Total cost was 290€ and it completely resolved the electrical issues. No more unusual failures or starting problems since the repair. For more specific advice about your Up, could you share: Battery age, Whether the charging system has been tested, If you notice any unusual alternator noise, Current battery voltage readings if you have them This would help determine if your case might need similar treatment or requires different components.

Last service was done at 119705km and they found no issues with the electrical system at that time. I recently checked the voltage with a multimeter and got fluctuating readings between 12.1V and 14.8V while running, which seems concerning. The alternator is making a slight whining noise under load. These symptoms have only appeared in the last 2 weeks, getting progressively worse. The problem clearly extends beyond just a weak car battery since even with engine running, I see these electrical system failures. The alternator failure seems more and more likely, especially given the circuit protection keeps triggering warnings. The timing suggests something suddenly started deteriorating rather than gradual wear. Thank you for sharing your diagnosis process, I will get the charging system tested professionally to confirm.

Thanks for the voltage readings, they definitely confirm what I suspected. Those fluctuations between 12.1V and 14.8V match exactly what I saw before my alternator failed completely. The whining noise is another telltale sign that matches my experience. The power surge pattern you describe is very similar to what damaged my car ECU. In my case, waiting too long led to more extensive electrical issues and higher repair costs. The circuit protection can only handle these voltage spikes for so long before components start failing. When my alternator was replaced, the mechanics also found: Damaged voltage regulator, Stressed battery cells, Minor damage to several electrical control units Total repair ended up costing 780€ including: New alternator with regulator, Battery replacement, System diagnostics, ECU inspection Getting it checked immediately is crucial, my delay caused additional electrical issues that could have been avoided. The progressive nature of your symptoms matches my timeline exactly, and these problems rarely fix themselves. Let us know what the professional diagnosis reveals. Based on the matching symptoms, I suspect you will need similar repairs to what fixed my car.

Thanks for the additional info about your electrical issue. Those voltage readings match up with what I experienced, normal range should be 13.8-14.4V. The fluctuating voltages combined with the whining noise strongly suggest alternator problems. A weak car battery alone would not explain these symptoms, since electrical failures occur even with the engine running. The multiple power surge warnings and circuit protection triggers point to failing voltage regulation. The timing of the issues, sudden onset and rapid deterioration over 2 weeks, suggests component failure rather than normal wear. High voltage spikes can quickly cascade into broader electrical issues if not addressed. Based on your description and my similar experience, I will definitely get the charging system professionally tested as soon as possible. I realize waiting could allow the electrical issue to cause more extensive damage to other components. Let me know what charging system diagnosis reveals. The shared experiences here have been really helpful in understanding what I'm likely dealing with. I suspect addressing this promptly will help avoid more costly repairs down the line.