VW Lupo Alternator Warning Signs & Charging Problems

Having some experience working on VWs, I encountered almost identical symptoms with my 2002 VW Polo diesel. The charging system was giving similar trouble, battery warning light, voltage drop issues, and dim headlights. After running diagnostics, the workshop confirmed a faulty generator (alternator) was causing these problems. The alternator was no longer providing sufficient charge to the battery, leading to starter motor problems and reduced engine performance. The complete repair included: New alternator unit, New drive belt, Battery load test, Full charging system check Total cost came to 960€, including parts and labor. Since the repair, all electrical systems work perfectly and the engine runs at full power again. To provide more specific advice for your Lupo: What is the current battery age? Have you noticed any unusual belt noises? What voltage reading do you get while running? Are there any other warning lights besides the battery? These details would help determine if your symptoms match exactly what I experienced with my Polo. A proper diagnosis of the charging system is crucial before proceeding with any repairs, as similar symptoms can sometimes stem from other electrical issues.

Last service was 3 months ago at 124943km. After checking my battery voltage, it reads only 11.8V when running, confirming your diagnosis about alternator replacement being needed. The alternator pulley also makes a slight whining noise during cold starts, which wasnt mentioned in my initial post. The serpentine belt shows signs of wear too, so it makes sense to replace both components at once. Thanks for the detailed breakdown. Will book it in for repairs since these symptoms match exactly what you described.

Thanks for the voltage reading, 11.8V while running definitely confirms the charging system issues we discussed. The whining noise from the alternator pulley is a telltale sign I also experienced before my repair. In my case, that noise got progressively worse over about 2 weeks before I had it fixed. Since your serpentine belt shows wear, replacing it together with the alternator is the smart move. When my alternator failed, the worn belt had actually started affecting other components it drives, like the power steering pump. The repair cost might be slightly lower than what I paid since current prices for VW parts have come down a bit. Based on recent quotes, expect around 850€ for a quality alternator, new serpentine belt, and labor. Quick tip from my experience: after the repair, make sure they test the charging system under load. My first repair attempt failed because they didnt identify a small wiring issue at the alternator connector. A proper load test will confirm the starter motor gets enough power and the engine runs at full capacity.

Following your situation closely, I ran those additional voltage tests you mentioned. My current reading of 11.8V while running, plus that whining noise from the alternator pulley during cold starts, really seems to match the alternator issue you experienced. I didnt mention this earlier, but the pulley has started making that distinct whining sound, especially when the engine is cold. Good call about the serpentine belt, mine is indeed showing wear marks, so replacing both components makes perfect sense. Since my car wont start properly and the charging system is clearly failing, I will schedule the repair work right away. The symptoms are identical to what you described, dim headlights, battery warning light, and poor starting performance. Your cost estimate around 850€ for parts and labor helps with planning. Will make sure they perform that full charging system test under load that you recommended. Thanks for sharing your experience, it helped confirm my suspicions about the alternator replacement being needed. Better to fix it now before I end up stranded with a car that wont start.