Audi A5 Cold Start Issue Points to Terminal 30 Circuit

I faced similar starting problems with my 2016 Audi A4 2.0 TFSI. The symptoms were identical, difficult morning starts despite a seemingly good battery. The root cause was a voltage drop in the wiring harness connecting to Terminal 30, which feeds constant power to the starter motor. A proper diagnosis revealed multiple issues: 1. Corroded battery terminals causing poor conductivity 2. Damaged wiring harness near the starter motor connection 3. Short circuit in one of the main power distribution points The fix required: Complete cleaning of battery terminals, Replacement of the affected wiring harness section, Fuse box terminal reconnection This was a serious electrical system issue that could have led to complete starting failure or potential damage to other electrical components. The voltage drop was causing excessive strain on the starter motor. The visual inspection often misses these problems because corrosion and wiring damage can occur in hidden areas. A professional diagnosis using voltage drop testing across the charging circuit is essential to pinpoint the exact fault location. Would strongly recommend getting a proper electrical diagnosis done, as these symptoms typically worsen over time and can leave you stranded.

Thanks for sharing your experience. That damaged wiring harness issue sounds exactly like what I dealt with. My repair also revealed problems with the charging system and required a circuit breaker replacement I hadnt expected. Did you track how much the full repair ended up costing? Also curious if youve had any electrical gremlins pop up since the fix? My power supply has been rock solid after the repair but always good to know what to watch for.

After seeing the mechanic, my electrical fault issues were completely resolved. The Terminal 30 continuous plus problem was fixed alongside a battery replacement, as it turned out to be heavily discharged beyond recovery. The total repair came to 290 Euro, which included diagnostic time and parts. Since the fix 8 months ago, the power supply has been working flawlessly with no electrical gremlins appearing. The ignition switch engages smoothly every time, even during cold starts. A thorough check by the mechanic also confirmed no lingering short circuit risks in the system. The circuit breaker replacement you mentioned is actually a smart preventive measure, it helps protect against future electrical issues that could damage the new battery or other components. The key is staying on top of battery maintenance now. Regular voltage checks and keeping the terminals clean have helped ensure consistent, reliable starts without any power delivery problems.

Based on the conversation, I went ahead with getting it properly diagnosed at a local garage last week. The mechanic found issues with both the starter motor wiring and some corroded connections in the main power supply line. Total repair came to 350 Euro including parts and labor. The fix involved: Replacing damaged wiring sections, Cleaning all power connections, Installing new fuse box terminals, Testing the complete charging circuit Car starts perfectly now, even on cold mornings. The electrical fault warnings have completely disappeared. Really glad I got it sorted before winter, definitely worth the investment rather than risking getting stranded somewhere. Big thanks to everyone who helped point me in the right direction with the diagnosis. Sometimes paying for proper testing saves money in the long run by fixing the real problem first time.