VW Fox Battery Drain Mystery: Weak Starts & Dead Power

I experienced similar electrical system issues on my 2013 VW Polo 1.6 TDI. The symptoms matched exactly, weak starting, flickering lights, and multiple dashboard warnings. The battery drain was getting worse each day, especially during cold morning starts. The root cause was a faulty battery sensor, which was sending incorrect readings to the car computer. This made the alternator malfunction, leading to improper battery charging. When left unfixed, a bad sensor can cause the battery to drain completely and potentially damage other electrical components. The repair involved: Testing the electrical system, Replacing the battery sensor, Recalibrating the charging system, Installing a new car battery since the old one was damaged This was a serious issue that needed immediate attention. Ignoring these symptoms could have led to being stranded with a dead battery or damaging the alternator. The battery sensor problem is relatively common in VW diesel models from that era. Getting it fixed at a certified workshop is crucial since they have the right diagnostic tools to properly identify and resolve electrical system issues. They can also check if other components were affected by the faulty sensor.

Thanks for sharing your experience. Similar problems happened to my Fox just 6 months ago. The mechanic found my vehicle battery was completely discharged due to a failing alternator. The battery terminals were also quite corroded which made the battery failure even worse. After replacing both the alternator and installing a new battery, the problems disappeared completely. No more weak starts or warning lights since then. Did you remember roughly how much the repair cost in your case? Also curious if you had any other electrical issues pop up since getting it fixed?

I'm glad I could help and happy to hear you got your battery drain issues sorted out. Since having the faulty battery sensor replaced for 315€ at my trusted mechanic, the electrical system has been working flawlessly. No more problems with weak starting or flickering lights at all. A defective battery sensor can be tricky to diagnose, but once fixed, it prevents the battery from heavily discharging like it was doing before. It's been over a year now and I haven't experienced any other electrical issues. The car starts perfectly every morning and all systems work as they should. Your case with the corroded battery terminals and failing alternator sounds more severe than what I dealt with. Good thing you got it fixed, corrosion at the terminals can definitely accelerate battery drainage and cause all sorts of electrical gremlins. Having proper diagnostic equipment is key for these electrical system problems. A professional shop can quickly pinpoint whether it's the sensor, alternator, or battery causing the issues.

After dealing with those frustrating battery problems, I finally took my Fox to a new mechanic who came highly recommended. The whole experience was much better than my previous repair attempts. The diagnostic showed my alternator was failing to properly charge the car battery, and there was heavy corrosion built up on the battery terminals. No wonder the car struggled to start each morning. The mechanic thoroughly cleaned the terminals and replaced both the alternator and battery. The total repair came to 480€ including parts and labor. While not cheap, it was worth every cent since the car now starts perfectly every time. No more flickering lights or error messages either. The new mechanic took time to explain everything and even showed me the worn-out alternator parts. It has been 6 months since the repair and I have had zero electrical issues. Really glad I switched to a more qualified shop that could properly diagnose and fix the low battery problems. The peace of mind knowing the car will start reliably is worth the investment.