Audi Q7 Battery & Electrical Systems Going Haywire

Had similar electrical system issues on my 2012 Audi Q5 2.0T. The symptoms started exactly like yours, weak starts, multiple dashboard errors, and dim headlights pointing to a potential dead battery situation. Initially thought it was just battery age, but after inspection found the battery sensor was defective. This component monitors battery charging status and controls the charging system. When faulty, it causes the alternator to improperly charge the battery, leading to low battery conditions even with a healthy battery. The fix required replacing both the battery sensor and battery terminals since corrosion had built up. After replacement, all electrical system issues resolved completely. This was a serious issue that could have left me stranded if not addressed, as the faulty sensor continuously drained the battery even when the car was off. Important to note, when battery charging issues occur in these Audis, its worth checking the entire charging system, not just the battery itself. The sensor issue is a known weakness point in several VAG models from that era. Testing the battery sensor output should be part of any electrical system diagnosis to avoid replacing parts unnecessarily.

Thanks for sharing that detailed experience with your Q5. I am quite sure I am dealing with something very similar in my Q7. Your hint about the battery sensor issue really got me thinking, as my discharged battery symptoms match perfectly. Before I take it back to the shop, would you mind sharing how much the repair cost in your case? Also curious if youve had any recurring car battery problems since getting it fixed? This could help me budget for the worst case and know what to expect. Looking back, I probably should have had them check the entire charging system during that first visit last month instead of just focusing on basic battery tests.

Since having the battery sensor replaced on my Q5, the electrical system has worked flawlessly. The heavily discharged battery issue was completely resolved, and I havent experienced any recurring problems in the charging system. The total repair cost was 315 Euro, which covered the new battery sensor and labor. While it might seem steep, its much more cost-effective than repeatedly dealing with a discharged battery or risking complete battery failure that could leave you stranded. The battery charge now maintains properly, and all those initial symptoms, weak starts, dash errors, dim lights, have disappeared entirely. Make sure to mention the possibility of a faulty battery sensor when you return to the shop. It could save time in diagnosis since these symptoms so closely match what I experienced. Investing in a proper fix for the charging system definitely beats dealing with ongoing battery problems or potential electrical system damage from constant battery drain.

Finally got the car back from the shop yesterday. Just like you suspected, it turned out to be a faulty battery sensor causing all those vehicle battery issues. The mechanic found significant corrosion around the sensor connections too, which was contributing to the battery drain problem. The total repair came to 295 Euro including a replacement battery sensor, cleaning of the terminals, and labor. While not cheap, its definitely better than facing repeated dead battery situations or getting stranded somewhere. Already notice a huge difference, the car starts strong, no more warning lights, and the headlights are back to full brightness. The mechanic also did a full charging system test to confirm everything is working properly now. Really appreciate the advice about checking the whole charging system rather than just assuming it was a low battery issue. Saved me from potentially replacing a perfectly good battery unnecessarily.