VW Polo Battery Sensor Issue Causing Starting Problems

I had a very similar issue with my 2013 VW Golf diesel last winter. With some experience working on VWs, I recognized those symptoms immediately. The slow cranking and flickering lights pointed to battery voltage regulation problems. Even though my battery charge was good, the voltage sensor was giving incorrect readings to the car's electrical system, causing erratic behavior. After monitoring the battery health for a week using a multimeter, the readings were inconsistent despite having a perfectly good battery. The workshop ran a complete diagnostic on the electrical system and confirmed the battery voltage sensor was faulty. The repair involved replacing the voltage sensor and recalibrating the charging system. Total cost was 315€ including parts and labor. Since then, starting has been smooth and electrical systems work perfectly. For your case, could you share: Current battery voltage readings if you have them, Whether the check engine light is on, Any error codes from recent diagnostics, If you notice the issue more during certain weather conditions This information would help determine if your symptoms match what I experienced and if the battery maintenance approach that worked for me might help in your situation.

I had a very similar issue with my 2013 VW Golf diesel last winter. With some experience working on VWs, I recognized those symptoms immediately. The slow cranking and flickering lights pointed to battery voltage regulation problems. Even though my battery charge was good, the voltage sensor was giving incorrect readings to the car's electrical system, causing erratic behavior. After monitoring the battery health for a week using a multimeter, the readings were inconsistent despite having a perfectly good battery. The workshop ran a complete diagnostic on the electrical system and confirmed the battery voltage sensor was faulty. The repair involved replacing the voltage sensor and recalibrating the charging system. Total cost was 315€ including parts and labor. Since then, starting has been smooth and electrical systems work perfectly. For your case, could you share: Current battery voltage readings if you have them, Whether the check engine light is on, Any error codes from recent diagnostics, If you notice the issue more during certain weather conditions This information would help determine if your symptoms match what I experienced and if the battery maintenance approach that worked for me might help in your situation.

Thanks for that detailed feedback. Just had my 95000km service done last month. When measuring my battery voltage it fluctuates between 12.1V and 14.8V which seems unusually wide. No check engine light, but I pulled error code P0622 with my scanner. The cold weather definitely makes it worse, below 5° the cranking is really sluggish. My voltage sensor readings are all over the place like yours were. Going to book it in at the workshop since the symptoms match so closely. The sensor replacement cost seems reasonable considering the diagnostic time needed. For anyone searching this issue later, make sure proper battery voltage testing is done before replacing parts. A faulty sensor can mask other charging system problems.

Thanks for that detailed feedback. Just had my 95000km service done last month. When measuring my battery voltage it fluctuates between 12.1V and 14.8V which seems unusually wide. No check engine light, but I pulled error code P0622 with my scanner. The cold weather definitely makes it worse, below 5° the cranking is really sluggish. My voltage sensor readings are all over the place like yours were. Going to book it in at the workshop since the symptoms match so closely. The sensor replacement cost seems reasonable considering the diagnostic time needed. For anyone searching this issue later, make sure proper battery voltage testing is done before replacing parts. A faulty sensor can mask other charging system problems.

Looking at your voltage readings, this is exactly the same pattern I saw with my Golf. Those fluctuations between 12.1V and 14.8V are a classic sign of a failing battery voltage sensor. The error code P0622 also confirms what my diagnostic revealed, an issue with the generator field/F terminal. The low voltage during cold starts matches my experience perfectly. The battery sensor gives incorrect readings to the charging system, so it cant properly regulate voltage output, especially in cold conditions. My voltage readings were similarly erratic before the repair, bouncing between 11.9V and 14.9V. The workshop confirmed the battery sensor was sending incorrect data to the ECU, causing the alternator to overcompensate. The 315€ repair cost was worth every cent. They not only replaced the battery sensor but also performed a full charging system calibration. This resolved both the cranking issues and the flickering lights completely. Since you already had your service done recently, the battery and alternator are likely fine. Getting the voltage sensor replaced should solve your issues just like it did for mine. Just ensure they do a proper calibration afterward.

Looking at your voltage readings, this is exactly the same pattern I saw with my Golf. Those fluctuations between 12.1V and 14.8V are a classic sign of a failing battery voltage sensor. The error code P0622 also confirms what my diagnostic revealed, an issue with the generator field/F terminal. The low voltage during cold starts matches my experience perfectly. The battery sensor gives incorrect readings to the charging system, so it cant properly regulate voltage output, especially in cold conditions. My voltage readings were similarly erratic before the repair, bouncing between 11.9V and 14.9V. The workshop confirmed the battery sensor was sending incorrect data to the ECU, causing the alternator to overcompensate. The 315€ repair cost was worth every cent. They not only replaced the battery sensor but also performed a full charging system calibration. This resolved both the cranking issues and the flickering lights completely. Since you already had your service done recently, the battery and alternator are likely fine. Getting the voltage sensor replaced should solve your issues just like it did for mine. Just ensure they do a proper calibration afterward.

Thanks for the input. Just wanted to close the loop on this issue. Got the car checked today and the diagnosis confirmed the battery voltage sensor was faulty. The readings were exactly as discussed, wild fluctuations between 12.1V and 14.8V. The workshop performed complete vehicle diagnostics and found no other issues with the charging system. Final repair cost was 295€ which included: New battery voltage sensor, System calibration, Full electrical testing After the repair, cold starting is perfect and the lights no longer flicker. Battery maintenance will be easier now with accurate voltage readings. The proper battery charge is maintained consistently, even in cold weather. Good lesson learned about the importance of proper diagnosis. What seemed like a potential battery health issue turned out to be just a faulty sensor. Thanks again for helping point me in the right direction with this electrical problem.

Thanks for the input. Just wanted to close the loop on this issue. Got the car checked today and the diagnosis confirmed the battery voltage sensor was faulty. The readings were exactly as discussed, wild fluctuations between 12.1V and 14.8V. The workshop performed complete vehicle diagnostics and found no other issues with the charging system. Final repair cost was 295€ which included: New battery voltage sensor, System calibration, Full electrical testing After the repair, cold starting is perfect and the lights no longer flicker. Battery maintenance will be easier now with accurate voltage readings. The proper battery charge is maintained consistently, even in cold weather. Good lesson learned about the importance of proper diagnosis. What seemed like a potential battery health issue turned out to be just a faulty sensor. Thanks again for helping point me in the right direction with this electrical problem.