VW Polo Alternator Failure Causes Power Loss and Dim Lights

I had a very similar alternator issue with my VW Golf TDI 2018. As someone with some experience working on car electronics, the symptoms you describe match exactly what I encountered, voltage drops, dimming lights, and charging system warnings. After noticing the first signs, I had the workshop perform a complete diagnostic of the charging system. The testing confirmed a failing alternator that was not maintaining proper voltage. The repair involved replacing the entire alternator unit, which solved all the issues completely. Total cost was 960€ including parts and labor. To properly diagnose your case, could you share: Current battery voltage when idling, Whether the battery warning light stays on constantly, If the starter motor sounds normal during cold starts, Exact error codes from the diagnostic scan This would help determine if your Polo has the same alternator failure I experienced or if there might be other components involved. The 2018-2020 VW diesel models shared similar alternator designs, so the repair process should be comparable. Before the full replacement, make sure the workshop checks the battery condition and tests for any shorts in the electrical system, as these can sometimes mimic alternator problems.

Last service completed 2 months ago. Just dealt with this alternator issue at 134590km. Thanks for the detailed info. Had the battery voltage tested, showing 11.8V while idling, which confirms your suspicion about charging system problems. The starter motor still cranks normally, but takes longer with each start. Got error code P0622 during diagnostic scan, pointing directly to alternator failure. The battery warning light flickers intermittently, especially when using electrical accessories. Had a mechanic verify, the alternator is indeed failing to maintain proper charge. Parts already ordered, scheduled for replacement next week. Good to hear a similar repair resolved your issues completely. Would you mind sharing if you experienced any engine misfire symptoms during your alternator problems? Getting occasional rough running when the battery low warnings appear.

Thanks for the follow-up. The engine misfire symptoms you mentioned were exactly what I experienced with my Golf TDI before the alternator replacement. When the alternator fails to provide consistent power, it can cause the engine management system to behave erratically, leading to those misfires. The 11.8V reading while idling is definitely too low, healthy systems should maintain around 13.8-14.2V. My Golf showed similar voltage drops before the repair. The flickering warning lights and extended cranking time match the progression of my alternator failure perfectly. The P0622 code confirms what we both experienced, a failing alternator unit. The repair resolved not just the charging issues but also eliminated those engine misfires and restored normal starting performance. The serpentine belt was also replaced during my repair as a precaution, since it connects to the alternator. On my car, the total repair time was about 4 hours. Just make sure they test the new alternator output under load after installation to verify proper charging. After 50000km post-repair, I have had zero issues with the charging system or engine performance. A quick tip from my experience: until the alternator replacement, try to minimize the use of high-draw electrical accessories to reduce strain on the failing charging system.

Your alternator symptoms match my case exactly. My voltage test showed 11.8V at idle and the starter also struggled more with each start attempt. The P0622 code plus the flickering battery warning definitely points to alternator failure, just like you experienced. Got some engine misfire issues too when the battery warnings show up. Good to know replacing the alternator solved similar problems on your Golf. My mechanic confirmed the diagnosis and has ordered the parts, scheduled for replacement next week. The repair cost estimate is close to what you paid at 980€. Really helpful to hear your alternator replacement fixed all those symptoms completely. Will make sure they check the serpentine belt during the repair too. Thanks for confirming my diagnosis and sharing your repair experience. Will report back after getting the alternator replaced to let others know how it went. For now, following your advice about limiting electrical accessories until the repair is done. Looking forward to having this charging system issue resolved like yours was.