Weak RSQ3 Starting Issue Points to Terminal 30 Problem

I had a very similar issue with my 2011 Q3 2.0 TFSI last winter. I have some experience working on cars, mostly basic maintenance and electrical troubleshooting. The symptoms you describe match exactly what I experienced, weak cranking and inconsistent starting. Initially thought it was just the charging system, but it turned out the battery was failing despite showing good voltage readings at rest. The workshop did a complete diagnostic which revealed voltage drops under load. They traced the issue through the entire starting circuit, checking the fuse box connections and wiring harness for any potential issues. In my case, the battery was not just discharged but actually defective, it could not maintain proper cranking voltage. The fix included: Full electrical system diagnostic, Battery load testing, New battery installation, System reset and adaptation Total cost was 290 Euro including parts and labor. Before suggesting more specific solutions, could you share: Battery age and type, Whether you notice any electrical issues when running, If the problem is more frequent in cold weather, Whether dashboard warning lights appear before starting attempts This would help determine if you are facing the same root cause or if your ignition switch might be the culprit instead.

Latest service was at 126000 KM. Based on the replies, my issue differs slightly. After the circuit breaker was checked, my workshop found corroded terminals inside the fuse box. The wiring harness connections at the starter were also damaged from heat exposure. The electrical fault turned out to be more complex than just a battery problem. The charging system tested fine, but poor conductivity through damaged wires was causing voltage drops during starting. Final repair included: Fuse box terminal cleaning, Partial wiring harness replacement, New starter solenoid Total cost: 450 Euro Starting has been perfect since the fix. Getting thorough electrical diagnosis saved replacing parts unnecessarily.

Thanks for sharing those details about your repair. The corrosion in the fuse box and heat-damaged wiring explains the intermittent starting perfectly. Had almost identical findings on my Q3 after deeper testing. What looked like a short circuit at first turned out to be deteriorated wiring causing resistance. The voltage drop during cranking was massive due to those bad connections, made the starter motor sound exactly like you described. One thing to watch, check the power supply connections at the fuse box every 6 months or so. The design tends to trap moisture there which can restart corrosion. A light coating of dielectric grease on the terminals helps prevent this. My repair costs were similar, around 420 Euro total. The wiring harness was the biggest expense but worth replacing properly rather than attempting partial repairs that might fail again. The starter motor itself was actually fine in my case too, just getting insufficient power. Good call having them trace the full circuit rather than just swapping parts. These starting issues can be tricky to diagnose without proper testing.

Thank you for explaining about your complex electrical issue. The short circuit caused by corroded terminals makes perfect sense given the symptoms. Replacing damaged sections of the wiring harness was definitely the right call versus just cleaning connections. My workshop found similar heat damage near the starter motor once they started tracing the power supply path. The ignition switch and charging system both tested fine, but the wiring insulation had deteriorated enough to cause resistance. Final repair breakdown: Cleaned fuse box terminals, Replaced damaged wiring sections, New starter motor connections Total: 450 Euro Really glad I had them do proper electrical diagnosis rather than just replacing the starter. The car starts perfectly now with no more weak cranking. Will definitely check those fuse box connections periodically to catch any new corrosion early. I appreciate everyone sharing their experiences, helped confirm this was likely an electrical issue before spending money replacing good parts unnecessarily.