Audi S6 Failing Alternator Drains Battery and Power

Had similar symptoms with my 2003 Audi A6 2.7T. The charging system showed clear signs of failure with identical issues, dimming lights and weak electronics pointing to a voltage drop. After proper testing, it turned out the alternator was failing to maintain proper voltage output. The repair involved a complete alternator replacement plus testing of the entire charging system circuit. The battery also needed replacing since the alternator issue had caused it to cycle too deeply. A voltage drop test confirmed the alternator was only putting out 11.2V instead of the required 13.8-14.2V under load. This was a serious repair that required immediate attention. Driving with a failing alternator risks complete electrical system failure and potential engine shutdown while driving. The starter motor can also get damaged from insufficient power during starts. The symptoms you describe match a classic alternator issue, and given the age of your S6, this is a common failure point. Would strongly recommend getting it diagnosed with proper testing equipment rather than risking further damage to other electrical components. Worth noting: Make sure they check the serpentine belt and tensioner while doing the alternator work, as these often need replacement at the same time to prevent premature alternator failure.

Thanks for confirming my suspicions about the alternator issue. Your A6 symptoms match exactly what I am experiencing. I recently had my S6 diagnosed and the charging system tests showed the alternator was failing, just like in your case. The serpentine belt looked worn too, so I am planning to have both replaced. Did you end up changing any other parts during your alternator replacement? And if you do not mind sharing, what was your total repair cost? Just want to make sure I am getting a fair quote from my shop. Also, have you had any electrical issues since the repair was completed? My starter motor seems a bit sluggish too, so I am wondering if that might need attention as well.

After getting the generator replaced on my A6, all electrical issues completely resolved. The repair cost came to 960 Euro which included a new serpentine belt and tensioner pulley. The charging system now maintains proper voltage and the car starts perfectly every time. I did not need any additional parts beyond those, but having the starter tested is smart since a failing alternator can strain it. My mechanic checked the starter during the service and confirmed it was still working within specs despite the previous low voltage conditions. Make sure they perform a full charging system test after the repair to verify proper voltage output. A properly functioning alternator should maintain 13.8-14.2V at idle. This prevents the battery from being drained and protects other electrical components. My car has been running great for months now with no dimming lights or starting problems. Getting this fixed promptly was definitely worth it to avoid more expensive electrical repairs down the line. The alternator replacement resolved all the issues you described, weak electronics, poor starting, and warning lights.

I took my S6 to the mechanic last week and got everything sorted out. The alternator was indeed the culprit, testing at only 11.4V output. Total repair came to 890 Euro including a new alternator, serpentine belt, and tensioner. The mechanic also tested my starter motor which thankfully checked out fine despite the strain from the low voltage. They did a full charging system diagnostic after the repair showing proper 14.1V output at idle. Car starts perfectly now with no more dimming lights or weak car electronics. All warning lights cleared up and the power is back to normal. Really glad I caught this alternator issue before it caused more damage. Much better experience than my last mechanic. They completed everything in one day and provided detailed testing results. Definitely worth fixing right away rather than risking further electrical problems.